Secret Agent "X" – The Complete Series, Volume 1

A monster of evil came to the nation’s capital. A green-masked ambassador from Hell’s own legation, followed by a horrible horde versed in the poison torments of the Far East! Even the police who sought to trap him did not guess the ghastliness of his real motive. That remained for Secret Agent “X” to discover as he prowled through a dark and sinister labyrinth of Washington espionage.

Chapter I

DARKNESS lay over Washington. Darkness that was a smothering black blanket ripped apart by sinister knife blades of lightning. A jagged streak empurpled the sky. It bathed the dome of the Capitol at the end of Pennsylvania Avenue. It etched the classic columns of the White House in lurid silhouette.

Thunder rolled in like a savage war drum. When it died away, echoes raced across the Mall toward the distant ghostly spire of the Monument. Trees moaned in the night wind. Rain lashed the empty streets in chill torrents.

The city seemed deserted. Its residents had taken refuge in their snug homes. They were ignorant of the strange, secret conference in session at the State, War and Navy Building. They were unaware of the nerve-racking tension that filled a locked and windowless room where seven men sat.

Five of these men were United States senators. One was a cabinet member close to the President. The seventh was an army officer attached to General Staff.

The army officer was concluding an amazing speech. He stared from face to face of the tense circle around him.

“Let me repeat,” he said, “that the discovery of Doctor Browning’s just before his death was quite accidental. His life was given to the study of radioactive substances. He was an authority on radium, thorium, and uranium. It was a radium-induced cancer that sent him to an early grave. But the destructive possibilities of radioactivity didn’t concern him. He was interested only in its therapeutic effects.”

The young officer paused, cleared his throat, and fingered the papers on the table before him.

“When Doctor Browning sensed the sinister powers of the ray amplification mechanism he had built, he was profoundly shocked. To make sure that his fears had a basis in fact he tested the mechanism on animals. He found that it caused complete and permanent paralysis of all nerve centers. He found that it turned living things into horrible hulks with a bare spark of life still remaining. He found, moreover, that it was effective at a great distance. He was about to destroy it when he was stricken by death himself. Fortunately, the United States government saw fit to confiscate the mechanism and the blueprint plans.”

The army officer sat down abruptly. In spite of the chill of the room, beads of sweat glistened on his forehead. He wiped them away and his hands shook nervously. A peal of thunder boomed far off on the horizon like deep-toned mocking laughter.

The gray-haired cabinet member at the table’s head rose. For a moment he, too, stared at the five senators. Then he spoke in a voice that seemed unnaturally dry:

“You’ve heard Captain Nelson’s testimony, gentlemen. You’ve heard reports and seen statistics showing what the mechanism of Browning’s can do. There’s no question, gentlemen, but that the United States has in its possession one of the most terrible offensive weapons on the face of the earth. A weapon, let me remind you, so ghastly, so inhuman, that it appears to be outside the pale of civilized warfare. The purpose of this meeting is to decide whether or not this weapon should be preserved or destroyed. What are your feelings in this matter, gentlemen?”

FOR a moment there was silence punctuated only by the faint footfalls of the armed guard outside and the muffled rumble of the thunder. The senators were grappling mentally with the appalling horror of what they had heard. They were visioning armies going down under the force of an invisible ray. Visioning strong men being turned into paralyzed, corpselike wrecks; men speechless, motionless, yet still alive — legions of the living dead.

White-haired, ruddy-faced Senator Blackwell, chairman of the committee, rose to his feet, fists clenched. He struck the table a terrific blow. His finely molded face was quivering with emotion.

“It must be destroyed!” he cried. “Get rid of it for all time. Burn the plans, sink the machine into the deepest depths of the sea. I don’t care how you do it — but destroy it!”

He sat down, breathing heavily. Three other senators — Dashman, Foulette, and Cobb, nodded instant agreement. But the fifth, Senator Haden Rathborne, a pale, saturnine man, shook his head. There was a fire in his eyes as he faced the others.

“Gentlemen,” he said harshly, “I understand your feelings. But war is war — and the instruments of war must be effective. We have machine guns, explosives, poison gas. Why not a paralyzing ray?”

Again Senator Blackwell became the spokesman for the others.

“Why not?” he shouted. “Because, as we’ve just heard, it’s inhuman, ghastly. Because we know that paralysis is one of the most horrible things that can afflict a man. Because it is a fate we wouldn’t wish even upon our enemies.”

Senator Rathborne jumped to his feet. The light in his eyes had become a living flame. He thrust his short-necked head forward, hunched his shoulders, and drew up his hands in a gesture of angry impatience. His voice rose in sudden, fierce emphasis:

“With war threatening in a dozen countries it is madness to destroy such a weapon. The interests of humanity? Very pretty, gentlemen — very pretty! But we have the interests of our own country to consider. If war should come we can’t afford to be white-livered and squeamish.”

Senator Cobb entered the discussion now. A round-faced little man, immaculately dressed, he stabbed a shaking finger at Senator Rathborne.

“Remember, sir,” he said hoarsely, “that civilian populations will suffer, too. You can’t prevent it. Do you care to contemplate women and aged non-combatants becoming paralytics? Do you care to picture thousands of innocent children made hopeless cripples for life?”

Rathborne instantly gave answer, his whole lean body trembling with fanatical zest.

“I’ve never sought popularity, Cobb,” he snarled. “I’m not a vote-snatching, favor-currying politician like some gentlemen I could name. I’m a man who speaks his mind. I advocate retaining and developing the Browning ray machine into an efficient weapon of war. In the next world conflict, the nation which inspires the greatest terror will win — the nation that breaks its opponent’s morale.”

Cobb stood speechless, confused. It was Blackwell who addressed the meeting for the third time. His face looked apoplectic. He struck the table, threw his shoulders back, and spoke in a voice that made the walls ring.

“Rubbish, Rathborne — utter rubbish!” he shouted. “It was Germany’s terroristic tactics — her submarines, her Zeppelins, her poison gas — that made the nations of the earth rise up to crush her in the World War! Countries will always combine to defeat a common enemy. Even if this were not so, the proud history of these United States wouldn’t allow us to stoop to the use of such a weapon. I move, gentlemen, that the Browning ray mechanism be destroyed for all time.”

Senators Dashman, Foulette, and Cobb leaped to their feet, cheering Blackwell. The cabinet man joined them. Captain Nelson, looking relieved, nodded his approval.

Only Senator Rathborne remained silent. His face wore the obstinate, sullen expression of a man who cannot accept defeat gracefully. But the motion was carried over his head. It was agreed by the senatorial committee that Doctor Browning’s hideous ray mechanism be destroyed.

RATHBORNE was the first to leave the conference room. He placed his broad-brimmed hat on his head with a vicious slap. He stalked angrily from the building. The others made their exits in pairs.

Rain lashed their faces. Wind pressed their garments to their bodies. But they didn’t mind the fierceness of the weather. They felt they had done a good night’s work. They thought they had settled an unpleasant problem. None of them guessed how soon the unseen spirit of horror was to stalk through the dark, deserted streets of Washington. None of them sensed that the lightning was like a demon’s winking eye and the thunder that followed it a peal of devilish, sardonic mirth.

But a few minutes after they had left the committee room a human cry stark with agony sounded in the night. It rose piercingly above the mutter of the thunder, died away into a weird echo that whispered along the now deserted street.

A patrolling cop two blocks away heard it. He turned alertly, staring into the murky gloom from beneath the dripping visor of his rubber-covered cap. The glistening black rubber of his cape swished wetly as he ran toward the spot from which the sound had issued.

There was no one on the sidewalk. His flash beam probed areaways; and suddenly he stooped down.

A sprawled, inert figure lay at his feet — a man. Under the glare of the electric torch, livid rivulets of crimson showed. They streaked the man’s cheeks, mingling with the rain, coming from a hideous wound in the left temple. The cop’s fingers groped hastily for the man’s pulse. There was no heartbeat. The man was dead.

One shrill blast on the cop’s whistle summoned the patrolman on the next beat. Then he ran to the phone box on the corner.

His call was relayed over many wires. It caused consternation in high circles. Hardly had the five senators reached their homes when a strange message was flashed to each.

“The Secretary of War requests your presence immediately!”

Wondering, filled now with a deep sense of foreboding, the senators responded. One by one their fast cars sped back along their tracks, and at the State, War and Navy Building they entered the same windowless room they had so recently left.

The secretary greeted them silently, his face grave and strained. There were odd, haunting shadows of uneasiness in his eyes. Not until they were all assembled did he speak. Then he stared fixedly into the faces of the five senators seated before him. He licked his lips, fumbled a moment with his watch chain, cleared his throat noisily.

“Gentlemen,” he snapped. “I have terrible news for you. You heard tonight the report that Captain Nelson gave us on the Browning ray mechanism. You heard what a devastating weapon it could become. You were shown the unpleasant statistics of experiments made on animals. Gentlemen, Captain Nelson has been murdered — the plans of the ray machine have been stolen!”

Chapter II

AT the moment this terrible news was being spoken, a fast sport roadster came to a screeching stop before the Army Air Corps base at Mitchell Field, Long Island.

A tall man muffled in a heavy overcoat leaped from the car. There was a suitcase in his hand. He walked with quick strides through the field gate toward a two-place army plane warming on the deadline.

Sparks from the throttled motor issued like a swarm of fireflies from the end of the hot exhaust stack. The pilot turned his head, nodding, as the tall man came up. He watched as the tall man climbed into the gunner’s cockpit. He listened for the snap of the safety belt, then bent over his controls.

The plane tore down the field, leaped into the night sky in a roaring zoom of power. It banked, straightened out, and began to climb. Its destination was Bolling Field, Anacostia, D.C.

The pilot had no idea as to the identity of the man riding behind. He was only obeying orders which had instructed him to wait for and pick up a passenger. If he thought at all, he supposed that the man was an embassy attaché or an important witness in some fresh financial scandal the Government was investigating. The pilot’s one concern was to see that the trip was made safely. It was a wicked night for flying.

Only one or two people in the world knew the identity of the plane’s mysterious passenger. These few were pledged to secrecy and silence.

In the passenger’s pocket was a telegram couched in secret government code. It was addressed to Elisha Pond, care of a bank in New York. It summoned him to Washington. Arrangements for the army plane had been made at the order of a high Government official.

Tonight the mysterious passenger in the gunner’s seat was a man of destiny. His movements in the next few hours might influence the lives of thousands of people. They might conceivably influence the future of a nation.

In appearance there was nothing extraordinary about the man. He was youngish, well built. He sat erectly in his seat, staring ahead into the dark night. The only odd thing about him was the intent, burning light in his eyes. This light seemed to indicate depths of intelligence, magnetism, and power.

Yet, inconspicuous as the man’s features appeared, they held infinite mystery. For the face that showed was not his real one. The man was disguised, so cunningly that not even the sharpest eye could have detected a flaw. The man was, in fact, a master of disguise — a master of a thousand faces. The man was Secret Agent “X.”

Who was Secret Agent “X”? For months past people had been asking that question. Criminals along the black byways of the underworld had asked it. They had learned to fear his name. Rumors had even spread behind prison walls, spread to the darkest and most evil dives. Gangsters had heard of Secret Agent “X.” Murderers had trembled at mention of him.

The police forces of a dozen cities had asked to know who he was. Detectives had suspected him. He had been hunted as a criminal. Crimes that he had never committed had been pinned on him until subsequent facts proved him guiltless. Yet no one could give an accurate description of him, for he never appeared twice alike. He was a man of a thousand faces — a thousand disguises — a thousand surprises. A man who was feared, hated, suspected, hunted. A man who guarded his identity as a precious secret.

There was the snapping of excitement in Agent “X’s” eyes tonight. Under the cognomen of Elisha Pond, in care of the First National Bank, he had received many telegrams from Washington. They came from a high Government official whose identity was also a secret.

Sometimes they asked that strange facts be unearthed. Sometimes they asked him to investigate mysterious crimes. But never before, since his perilous career as Agent “X” had begun, had he been summoned to the capital. Something unusual was in the wind. Some case of greater import than any he had ever tackled impended.

Blood raced through the Agent’s pulses as the swift plane tore through the sky. Its whirling propeller sliced the sheets of rain. Lurid flashes of lightning began to show on the horizon. They shed a ghostly light on the wings; made the pilot ahead look like some crouching, helmeted monster.

And the Agent watched the ship’s course with the eye of an expert. If anything should happen to the army flyer up front, Agent “X” was capable of flying the ship himself.

They were following the shining ribbon of a straight double-tracked railroad. A fast passenger train showed beneath them. It was forging ahead at seventy miles an hour. But it seemed like a crawling, phosphorescent caterpillar as the army plane overtook it, and left it far behind.

In less than two hours a searchlight beacon showed on the horizon. It swung rhythmically across the heavens in conflict with the lightning. Peering over the plane’s cowling, minutes later, Agent “X” saw the flood lights of a Government field below. He saw the Washington Monument on his left, saw the gleaming surface of the Potomac River.

The plane began to descend. It banked, nosed into the wind, slid downward out of the night like a huge bird. Landing lights on its wings winked on and off. Other lights answered below.

The velvet-smooth surface of the field swept up. It was glistening with rain. The plane’s air wheels touched the ground. They lifted, touched again, settled. The plane taxied up to the hangars, fishtailed to a stop.

AGENT “X” leaped out. For a moment he looked around. A curious mechanic was moving forward. An officer, protected from the chill drizzle of the rain, stared at him from an open doorway. Then he saw a man in a glistening slicker running toward him.

“X,” who never forgot a face, stared intently. When light from the hangar’s open doorway fell on the man, “X” nodded to himself. The approaching figure was someone he knew — a trusted Department of Justice operative named Saunders; a man who had often been active in the dangerous field of counterespionage. On at least a half dozen occasions in the past, Agent “X” had talked to him.

But Saunders’ face was a blank when he came up. He didn’t recognize Agent “X.” The Agent’s masterly disguise fooled him. Saunders, thick-set, powerfully built and sandy-haired, peered under his wet hat brim.

“Are you Mr. Pond?” he asked.

The Agent nodded.

“I was told to meet you when you landed. I’ve got a car out in the street. But first, if you don’t mind—”

Again the Agent nodded. He knew what Saunders wanted. Caution was ingrained in the men who worked for the Federal bureaus. “X’s” hand dived into his pocket, came out grasping a wallet. From it he drew a card bearing the name of Elisha Pond. Saunders didn’t know that this was one of a dozen aliases. He didn’t know that the man called Pond carried other cards which he could have produced just as readily. He didn’t know that the man before him was Secret Agent “X.” He was merely obeying orders from a superior, as the pilot of the army plane had done.

“O.K.,” he said. “Step this way if you please, sir. It’s a nasty night, isn’t it?”

“Yes,” said the Agent grimly. He had an idea it was nastier than Saunders realized. He sensed strange, dark things in the air. He followed the stocky form of Saunders to the waiting car, a small, weather-beaten coupé.

“My own bus,” said Saunders proudly. “She doesn’t look so nice, but she’s a sweetheart on the road.”

Both men climbed in. Neither of them saw the shadow that moved along the hangar wall. Neither of them saw the dark, intent face that gleamed for a moment under the splashing drops of the rain.

There was a public telephone booth in a small cigar store opposite the field gate. As Saunders’ car splashed away, the shadow by the hangar wall ran over to the booth. In a moment he was speaking softly into the mouthpiece of a phone, using a foreign tongue. Another man, a half-mile away, was answering him, also in the same tongue. The second man hung up, slipped out into the dreary darkness.

Saunders tried to make conversation as he and Agent “X” sped along. “X” answered only in monosyllables. He was oppressed by a sense of impending trouble, wondering about the mysterious reason for his summons to Washington. He liked Saunders, but the man was only a small cog in some vast thing that was under way. The sandy-haired Federal operative lighted a cigarette. He sent the little car whizzing along, driving with careless ease.

It was Secret Agent “X” whose eyes roved the street ahead with the closest attention. It was “X” who first saw the dark car pointed at a crazy angle toward the curb. For a moment his fingers closed over Saunders’ arm.

“Someone’s skidded,” said Saunders. “And nearly smashed up.”

A man in a chauffeur’s uniform was bent over one wheel of the car ahead. He straightened, raised a hand in signal.

“They’re in trouble,” said Saunders. “Let’s see what’s the matter.”

He braked his little car, began to slow down. The Agent’s eyes had become burningly bright. But the chauffeur looked all right. He was dark-skinned. He seemed to be a mulatto. Saunders brought his car to a stop, cranked down a window.

“What’s the trouble, fellah?” he said.

The brown-skinned chauffeur came forward, holding something in his hand.

“Look,” he said. “Broken!”

He thrust his hand through the side window of Saunders’ coupé, opened the fingers. Then it was that Agent “X” hissed a sharp warning; but he was too late.

Something crackled in the brown-skinned man’s hand. It was like a dried puffball. A jet of brownish powder squirted from its collapsed sides. The powder filled the interior of the car. It went into the two men’s faces, blinded them as though hot needles had been thrust against their eyes. Saunders swore fiercely and lashed out with his fist.

“You double-crosser. I stopped to help you and—”

WORDS choked in his throat as the brownish powder passed between his lips. Agent “X” did not try to speak. He jerked at the car’s door, tried to get out, hoping that the night air and rain would clear his vision. He rubbed at his eyes with one hand, but it only seemed to drive the hot needles deeper into his nerves.

Dimly then he heard the sound of running feet around him.

He heard crisp orders shouted in a foreign tongue that made him start. A master linguist he had a basic knowledge of many languages. This was one he had heard before, but it seemed out of place, fantastic in his present surroundings. The brown-skinned chauffeur had been joined by others.

Hands caught hold of Secret Agent “X.” He lashed out with his fists, tried to fight free; then something was thrown over his head. A noose was jerked around his neck. He had a sense of enveloping cloth. A pungent, smothering smell was in his nostrils. It was like a strange, Oriental incense; but the sweetish odor of it was cloyingly oppressive.

He raised his hands, tried to pull away the hood that had been flung over his head. The dizzyingly sweet odor in his nostrils was filling his lungs now, choking off breath, making him reel on his feet.

Saunders beside him gave a hoarse, gurgling cry. He, too, had been attacked in the same way.

Blinded, smothering, Agent “X” was at a hopeless disadvantage. The onslaught had come before he had been on his guard, before he had conceived of the possibility of any enemy being present.

Cold fury filled him. He battled desperately to keep his faculties, to free himself from the smothering hood before darkness came. But the fumes in his lungs were mastering him. He slipped on the wet pavement, sank to his knees. His legs seemed to crumple under him. As blinding lights danced before his pain-racked eyes he fell into the black depths of unconsciousness.

Chapter III

HORROR beat upon him when he woke up. He had a sense of appalling catastrophe. He had lost all track of time. He seemed to be in a dark, still room. Then he became conscious of a sound. A man’s voice, low-pitched and precise.

The Agent’s eyes still burned, but when he raised inflamed lids he found that he could see. He started, and breath hissed between his teeth. He was in a room. It was a man’s voice he heard. And he saw in that first instant of returning consciousness that both he and Saunders were prisoners. There were steel handcuffs on his ankles and wrists. These were attached to rings in the wall behind; Saunders looked like a man stretched out on a crucifix. His head still hung down.

Then “X’s” eyes swivelled again to the man who was speaking. His attitude was as calm as the quiet tones of his voice, but his appearance made the Agent’s body grow rigid. For the man wore a green mask over his face. It was a livid, poisonous green, like the scales of some reptile, and, through slits in the mask, his eyes glittered as coldly and evilly as the beady eyes of a snake.

“You have waked,” the man was saying. “Your friend is waking also. You will now be able to answer questions I shall ask.”

Agent “X” turned his head. Saunders’ eyes, red and inflamed, were opening.

“What the hell—” he muttered. “Say, what’s this. You—”

The man in the green mask held up his hand. His eyes glittered behind the green of the cloth that covered his face. There was a measured inhuman dryness in his speech.

“Wait,” he said. “It is not for you to ask questions. That is for me. You need only answer.”

“I’ll answer nothing,” said Saunders. “I’ll see you in hell for this.”

“That may be,” said the green-masked man quietly. He chuckled, and there was something about the sound of that chuckle that tightened the skin along Agent “X’s” spine. He had been in the presence of some of the world’s most desperate criminals — men without heart or soul. He sensed now that he was in the presence of a murderer. He muttered a warning to Saunders.

The green-masked man turned on him.

“You need not be afraid to talk — Elisha Pond,” he said. “Your secrets are known already. You were summoned to Washington tonight for a special reason. You are the man about whom strange rumors have circulated, I think. You are called—”

The green-masked man stopped speaking for a moment and walked forward. He probed with tense, inquisitive fingers, picked at the lifelike plastic material on the Agent’s face.

“That is a disguise you are wearing — a most remarkable one. It is my belief that you are the man called Secret Agent ‘X,’ the man, they say, who can make himself up in a thousand different ways.” Green Mask’s chuckle came again. “Whether you talk or not now, Elisha Pond — it is unimportant. You will talk later, when I am ready — and if I give you another chance. Look!”

The man lifted his hand. In it was the telegram that had brought Agent “X” to Washington.

“Code!” the green-masked man said. “Government code. Very ingenious, isn’t it? Very difficult to read — but listen.”

In a clear voice the man who had captured Agent “X” and Saunders began to decipher the message on the telegram — the message instructing “X” what to do in a certain room of a certain house upon his arrival there. It was from a high and mysterious Government official. The green-masked man read it as easily as though it had been addressed to him. Then his voice grew harsh.

“This paper has saved you some unpleasantness. If I hadn’t seen it, and if you still refused to talk, I would take means to make you. For you are an important man, Elisha Pond. Otherwise you would not have been summoned to Washington. You are expected to perform a great service for your country. But it is evident to me that I know more at the moment than you. The rest I shall learn from the sender of this telegram — and from your friend here.”

Again Saunders spoke, fury mottling his face. “Not from me, you won’t — you double-crossing mug.”

“I don’t like your speech,” said the green-masked man quietly. “You were instructed to take this gentleman, Elisha Pond, to a certain address. You will now give me that address.”

“You heard me,” said Saunders. “Come over here and I’ll give you a poke in the eye.”

“Fool!” rasped the Green Mask. He clapped his hands suddenly. The door of the room opened. Four figures glided in. The eyes of Secret Agent “X” stared at them burningly. Saunders gaped in amazement. If this had been a weird, drug-distorted nightmare, the four who had entered could not have been more grotesquely horrible. They, too, wore green masks, but not a simple cloth mask like the man in the chair. Hideously carved devil faces of some thin wood covered their features. They looked savage, barbaric. Leering mouths, huge noses, distended nostrils — with the sinister glitter of their own eyes flashing through holes in the wood. One of them spoke — and Agent “X” recognized again the foreign tongue he had heard before.

The man in the chair gave answer, using the same strange dialect.

“Chinks!” breathed Saunders — but “X” knew he was wrong.

The man in the chair turned again, faced Saunders.

“I give you one more chance,” he said. “Will you talk or shall the Kep-shak be used — the pollen of the blossom that loosens men’s tongues?”

A cold sweat stood out on the Agent’s forehead. Some inkling of what was to ensue filled him. He turned his head toward Saunders.

“Talk,” he said. “Tell him what you know!”

This wouldn’t be much — only an address. Its concealment was not worth a man’s agony. But Saunders shook his head. He was a powerful man, arrogantly confident of his own physical endurance.

THE green-masked man in the chair clapped his hands again. The four others stepped forward. One of them drew a knife, slit the sleeves of Saunders’ coat from shoulder to wrist, laying bare his arms. Another drew something from behind his back that was like a tiny devil’s claw. With an abrupt, expert stroke he drew it across Saunders’ skin, leaving a line of red scratches. A third man came forward with a metal box in his hand. He lifted the cover, drew out a pinch of grayish powder.

“Talk!” said the Agent again. “Talk, Saunders.”

The thick-set Federal man gritted his teeth. His lips remained locked.

The man with the pinch of powder made a swift motion. He tossed the powder on the scratches along Saunders’ arm, rubbed it in with his thumb, stepped back. A slow change came over Saunders’ face. The muscles in his cheek began to tense. His body began to move. He writhed in the steel bracelets that held him, bucking his shoulders up, trying to tear his wrists loose. But the cuffs were locked tightly. The strong steel held.

His lips opened then. Breath whistled between his teeth.

“God!” he muttered. “God!”

The ruddy glow of his face was paling slowly now. Beads of sweat stood out on his skin. Agent “X” tried desperately to work loose, to aid him. But the steel of the handcuffs bit into his own skin. They held tight.

“I’ll talk,” said Saunders with a sudden groan. “You win, Green Mug. I’ll talk.”

The words were wrenched from his lips by pain. He was a brave man, but the agony of a strange, exotic drug seeping into his veins through the scratches in his arms was too much. He babbled the address to which he had been directed to take Agent “X.” The green-masked man in the chair nodded. Agent “X” listened. Then the green-masked man spoke.

“You are a fool, Saunders. I don’t like fools. And you would be a nuisance if you lived. Also your death will be a lesson — to Elisha Pond!”

Horror crawled along the spine of Agent “X.” He had feared something like this. A cry sprang to his lips.

“If you do, Green Mask — I’ll see that you die yourself.”

Green Mask bowed ironically. “Another fool,” he said. “Look — and profit by what you see!”

He gave a low signal. The man with the powder stepped forward. Another pinch of the hideous gray stuff landed on Saunders’ tortured flesh. A groan came from his bloodless lips. He writhed horribly, tried to speak, but only a discordant babble came from his quivering mouth.

Agent “X” strained until veins stood out on his forehead, until the handcuffs bit cruelly. He called harshly for this terrible thing to stop. Green Mask did not answer. The four others were silent, their glittering eyes turned upon their victim.

At the last, Agent “X” did not look. Horror, nausea, weighed him down. The hissing gasps that came from Saunders’ throat seemed to lash the still air of the room. The walls seemed to throw the sound back in whispers of hellish laughter. Then silence followed, and when Agent “X” looked again, Saunders’ powerful body hung slack in the steel cuffs that held him. Saunders was dead.

Weak himself from the ghastliness of what had taken place, Agent “X” sagged in his fetters. He had faced death and torture in his life, but he could not calmly see others suffer.

The green-masked man spoke a low order. The four who had performed his bidding disappeared as they had come. Green Mask arose calmly. He slipped into a hat and coat he had thrown over the back of the chair. His glittering, evil eyes became fixed on Agent “X.” Agent “X” answered the look with fierce, silent hatred. The green-masked man buttoned his coat leisurely, turned his hat brim down.

“Let this be a lesson,” he said. “I go now to receive the instructions meant for you. I go to learn exactly why you have been summoned by plane to Washington. And if the reason is what I think, I will have use for you later.”

With a mocking salute, the man turned and strode across the still room. An instant later a door opened, closed, and was locked. It was followed by the sound of receding footsteps.

Chapter IV

AGENT “X” stared at his surroundings. The room he was in was bare, except for the one chair and a small table. There were no sounds, no street noises. Apparently the green-masked man had taken the others with him, left no guards, trusting to the strength of those forged steel handcuffs.

The Agent tested them. They were locked so closely to the flesh that they made painful pressure against his skin. The metal rings behind him were bolted into beams in the wall. He was apparently a hopeless captive. He rolled his eyes toward the still form of Saunders, cursed silently under his breath. He had seen many men die, but few as horribly as this.

Then Agent “X” began to move. He arched his body backwards. He thrust his hands down and brought his heels up. He could touch his shoe with his finger tips now. The steel cuffs cut cruelly into his wrists. He ignored the pain, stretched down farther still.

The fingers of his right hand groped along his left shoe sole. They paused, pried the leather of the sole apart at a point just in front of the heel. Working laboredly in his cramped position, he slipped something out. It was a four-inch piece of metal — a file. One side of it was highly tempered steel. The other side had a crystalline black substance set into it, held by grooved edges and mineral cement. It was a sliver of black diamond, thin as isinglass, but with a finely toothed cutting edge that was fashioned to rend the hardest of metal.

Turning this file in his hand, holding it in tense fingers, Agent “X” pressed the diamond-set edge against the connecting links of his handcuffs. With a steady, rhythmical movement he drew it back and forth and felt the tiny crystalline teeth bite into the metal. Minute flakes of steel fell away. The groove that his diamond file made grew deeper and deeper.

At the end of ten minutes of patient effort, the links of the handcuffs parted. He breathed deeply, flexing his cramped arms. The metal bracelets were still on his wrists. There wasn’t time to sever them now. He bent and attacked the steel links that connected the fetters on his ankles.

He had more room to work now, more leverage. Muscles in his arms and shoulders stood out as he drew the diamond-studded file across the metal in short, powerful strokes. He freed himself of the ankle cuffs in half the time it had taken to do the others. He stood erect — free — and the burning light in his eyes became like a hot flame. He moved close to Saunders, felt the man’s pulse to see that he was surely dead. The glassy, staring eyes of the Government operative were proof enough. Standing erect, face muscles rigid, Agent “X” seemed to be making a silent pledge.

Then, with the steel bracelets unconnected, but still on his wrists and ankles, he strode across the room. The door was locked on the outside, but locks were no impediment to the Agent. He drew a set of slender chromium tools from the lining of his pocket. With the head of one, bent like a blunt fishhook, he picked the lock and opened the door.

There was a hallway outside. It was dark and still. The Agent picked up his suitcase which stood in a corner. The disordered state of its contents showed that the green-masked man had gone through it.

Agent “X” turned it upside down, pressed metal studs on the bottom, then breathed quickly.

The mysterious criminal had missed the narrow, cleverly hidden false bottom where many of Agent “X’s” elaborate make-up materials were hidden. Only careful measurement of the sides of the suitcase would have revealed that.

With his luggage in his hand, Agent “X” catted into the dark hallway. He passed along it cautiously, ears and eyes alert. He encountered no one. He was in an old, deserted house. The masked torturers had gone.

AT the end of the hall he came to a street door. Lightning showed a vivid purple streak across the bottom of the door. He heard the dull and distant rumble of thunder.

He opened the door cautiously, stared out. The house faced on a dark old street in a part of Washington he was not familiar with. But there was no one in sight. The Agent slipped down the steps, crossed the street, and moved quickly ahead. He hated to leave Saunders behind, but the man was beyond aid now — and there was strange and vital work to be done.

He walked five blocks, then plunged into a corner drug store. He found a telephone booth and made a quick call, dialing a number not listed in the public directory.

A masculine voice answered him. It was a deep voice, with a note of quiet power in it, a voice known to Agent “X” only as “K9.”

In clipped sentences Agent “X” told of their capture, Saunders’ brutal murder, and his own escape.

The deep voice of “K9” gasped out a hoarse curse. “Saunders killed!” A silence followed. “X” could hear the harsh breathing of the man at the other end. Then the voice resumed: “Your impersonator failed to pass the tests. I grew suspicious, gave him no information, but—”

“He escaped!”

“Yes!”

“And your orders for me?”

“Come immediately to the appointed place. There is no time to lose now — after what has happened. We don’t know who this man is — or what he’ll do next.”

Agent “X” left the telephone booth quickly. He found a taxi. In it he was whirled through the night-shrouded streets of Washington to the address that was on the telegram.

He stopped the cab a block away, got out, and walked ahead cautiously. His quick brain was active. The green-masked devil would hardly be waiting here to intercept him — for he would suppose that the man he knew as Elisha Pond was still a prisoner.

Tense and alert, the Agent ascended the steps of a big old-fashioned house. At his ring an elderly servant opened the door. With a brief nod to the man, Agent “X” entered and walked directly to a room on the third floor. The room was furnished, but there was no one in it. Agent “X” closed and locked the door.

HE strode to an old-fashioned desk against one wall, seated himself in a chair before it. He knocked on the desk four times, a space, then four times more, as the telegram had instructed him. Then he waited.

As though ghostly fingers were moving it, a small drawer in the desk was pushed out toward him. From a hollow space behind the drawer a voice issued. It was the same deep voice that had spoken to “X” on the telephone.

“The countersign?”

“The thirteen original States,” answered “X.”

The drawer moved back, its front coming flush with the edge of the desk. There was a second of silence, a slight rustling sound, then the drawer moved into sight again.

It contained a piece of paper this time. On the paper a strange, disordered arrangement of numbers and figures were written. They belonged to no known Government code or cipher. They had been devised to fill a unique and special need.

“Read,” said the voice behind the desk.

Agent “X” took the paper from the drawer, studied it an instant, and spoke in a clear voice: “He is trampling out the vintage—”

With a pencil he wrote beneath this sentence, using the same strange symbols, “where the grapes of wrath are stored.” This line from the “Battle Hymn of the Republic” was the oral and written test the deep-voiced man had mentioned.

Agent “X” pushed the paper back into the drawer and the drawer disappeared. There was another moment of silence and the voice behind the desk spoke again: “Correct!”

“I am listening,” said Agent “X.” He had given proper identification. He was in communication with a trusted Government official, one of the few persons in the world who knew the real nature of his desperate and dangerous work.

The deep voice began to utter short, swift sentences.

“Two men have been killed tonight. Saunders was not the only one. The first was a Captain Nelson of General Staff, a man bearing important papers — the loss of which form a terrible threat to the safety of this country.”

At mention of the officer’s name, Agent “X” tensed, and asked a sudden question.

“Was it John Bernard Nelson?”

“The same — you knew him?”

“Yes.”

A shadow came into Agent “X’s” eyes. He had known Nelson back in the days when the world was bathed in the red carnage of war. He had known him as a high-spirited officer, brave, honest and loyal. And “X,” who never forgot a face, saw the features of Captain Nelson in his mind’s eye now. It added a personal touch to the mystery and horror of what had occurred tonight. Was this man another victim of Green Mask?

“How was he killed?” asked “X” harshly.

“By a blow on the head.”

The voice of “K9” began to give details then, details of the Browning ray mechanism, and the theft of the plans. When he had finished, “X” asked an abrupt question.

“Who are the suspects?”

A pause followed this query. The man who spoke through the drawer seemed to be thinking, pondering.

“It is a delicate matter,” he said at last. “That is why you were summoned, Agent ‘X.’ It is a matter that cannot be handled in the regular way. Five senators were in that room. Until this thing is settled, until the stolen plans are recovered, suspicion rests upon them all.”

“Their names?” asked Agent “X” quickly.

“Blackwell, Dashman, Foulette, Cobb, and Rathborne.”

“What line of investigation do you recommend?”

Again the voice was silent for a second. The answer it gave was tentative, reluctant.

“Senator Dashman was a friend of Captain Nelson’s. It was he who was influential in getting Nelson appointed to General Staff. He of the five would have been most likely to know in advance any movements the captain might make.”

“Anything else?” asked the Agent.

“One more thing! Captain Nelson has been seen in the company of a woman named Lili Damora. Investigate her, also.”

“I will,” said “X” quietly.

HE was beginning now to understand the importance of his summons to Washington. He was beginning to realize the extreme difficulty of this task that had been wished on him. The deep voice of the man behind the desk came again, quivering with suppressed emotion.

“You now have the facts, Agent ‘X.’ The rest is up to you. Terrible as the death of Saunders was, your task is greater than the mere pursuit of a murderer — a thousand times greater. It may be too late. Doctor Browning’s secret may already have left the country. In any event, menace hangs over America. If these plans fall into the hands of an enemy country — if war should come with that country — then untold horror will befall your fellow citizens. Do all you can to recover them. Leave no stone unturned. Stand ready to give your life, if necessary. That is all, Agent ‘X.’”

The voice ceased speaking. The drawer closed slowly. Trembling slightly, Agent “X” arose. It was not fear of death that made him tremble. Death he had faced often — on the flaming battlefields of France, in strange, dark alleys of the underworld, high in the air, deep in the sea. Years ago doctors had predicted that death would come from the wound in his side where he now bore a livid scar. The only fear that influenced him was the fear of possible failure — the fear that he was too late.

He descended the stairs of the house, left it as he had come. He strode off resolutely into the night. Down the block he signaled a cab. He gave the junction of two streets as his destination. There he changed to another cab. He did this twice more, keeping a cautious watch behind, taking precautions against the possibility of pursuit. The man in the green mask was constantly in his mind.

AT an address in a street of furnished apartments Agent “X” stopped at last. He took a key from his ring, entered the door boldly, went to an apartment on the second floor. Here was proof of the far-sighted policy he pursued in his strange warfare on crime.

The apartment was small but completely and comfortably equipped. Dust on the floor and furniture showed that it hadn’t been occupied for months. The Agent went to a closet, drew forth a wardrobe trunk. In it, packed closely and carefully, were dozens of suits and uniforms. It might have been the wardrobe of some master character actor.

He drew from it a trim army uniform. It had a captain’s insignia on the shoulders. The silver star and gold coat of arms of the General Staff were on the collar. In the pocket of the uniform were papers denoting the fact that its wearer was Captain Stewart Black. They were in good order and would pass inspection anywhere. As an army officer of General Staff, “X’s” movements were less liable to be questioned.

Before putting the uniform on, he opened the false bottom of his suitcase again. From it he took a small, collapsible, three-sided mirror, then an array of pigments, transparent tissues, and volatile plastic substances. Here was all the paraphernalia of a man who was a master of disguise.

He made sure the door was locked, set his mirror up. Then his long, powerful fingers went to work. He removed the disguise he had worn upon his arrival in Washington. For a moment, under an overhead light, his real face was revealed — the face that not even his few intimates ever saw. It was a singularly youthful face except when the light fell on it at an oblique angle. Then new planes were brought out. They showed marks of maturity and strength, with lines that were faint but recognizable records of countless strange experiences and adventures.

On these features that were really his own, he began building up a new face. The pigments came first, changing the color of his skin. Then strips of tissue-thin adhesive, creating new muscular contours. Then the mysterious volatile substance that dried almost instantly. The substance so flexible that it responded to every facial movement. He had the rugged, blunt features of a hard-bitten army officer now. Once again Agent “X” had wrought a masterly disguise.

In his natty uniform he seemed to have stepped straight from the General Staff offices, or from some drill ground. But even the uniform was not as simple as it looked. It contained secret, hidden pockets. Into these Agent “X” transferred certain small things that he carried in his other suit. There was even material for a quick change of disguise, if that became necessary.

Leaving his apartment quickly, he summoned another cab and gave the address of Senator Dashman’s home.

Rain still spattered on the pavement. Lightning flashed on the horizon. The storm that refused to leave the vicinity of the city seemed an expression of the menace that hung over the nation’s capital.

The cab sped along wet, glistening streets, came at last to a big house in a fashionable suburb — a house that expressed the dignity of a man who was one of the country’s lawmakers.

Agent “X” strode up the steps and pressed the bell. He had begun his campaign of action. He had a pretext for his visit to Senator Dashman carefully thought out. His inquiries about Captain Nelson would seem natural and in order. But it was seconds before his signal at the bell was answered.

Then a scared-faced, trembling servant came to the door. He was a colored man with features that showed the dusty grayness of fear. He stood on the threshold, making ineffectual motions for “X” to enter.

“X’s” muscles grew rigid. He sensed in that first instant that something was wrong.

In quick strides he brushed past the servant, entering the carpeted front hall. A group of white-faced people were crowding close to a doorway across the hall. They turned as Agent “X” came toward them. He grasped the arm of a young man.

“What is it?” he barked. “What’s the matter?”

The young man’s voice rose hoarsely. He raised a trembling hand and pointed through the doorway.

“There has been a robbery — and — look!”

Agent “X” followed the direction of the man’s shaking finger. An older man was seated at a desk in the room beyond, a man whose face “X” had seen in the papers many times. A man whose photograph he had in his possession, as he had the photos of all important Government officials. Senator Robert Dashman.

In that first swift glance Agent “X” saw why these men and women in the hallway were crowding close with a look of fear in their eyes. For Senator Dashman was toppled sidewise in his big armchair. His eyes were wide-open, glassy. His skin had the leaden hue of putty, and from his distended nostrils and open mouth came the hoarse sound of stertorous breathing. Senator Dashman was paralyzed — a horrible living corpse.

Chapter V

AGENT “X” stood stunned for a moment. There was a ghastly suggestion in Dashman’s stricken state. Was this the work of the terrible Browning ray? Doubt came instantly. How could it be, since only the plans of the ray mechanism had been stolen?

Agent “X” pressed forward into the room where the senator sat. A white-faced, trembling girl whose features showed a family resemblance hovered by his chair. “X” looked at the girl and said quickly, “A doctor should be called at once.”

The girl nodded. “One is on the way. He will be here any moment. And you—”

“Captain Stewart Black,” said the Agent. “I came here to question your father about—”

He paused and turned to stare at the group in the doorway. ln the first moment of excitement he had made no close inspection of those in the house. Now he stood rigidly transfixed, his face muscles stiffening.

A blond, powerfully built man was in the group. There were three others — two young women, one of whom he knew by sight, and the dark-haired young man whom “X” had first questioned. But the blond man was the focal point of interest.

The man’s face, too, was familiar to “X.” There had been a change, a drastic one. Plastic surgery had evidently been used. The chin and nose were different. But to “X,” who had made a life study of facial lines and planes, even the magic of the surgeon’s scalpel was not sufficient to conceal true identity. He had seen this man before.

Names, faces, dates flashed through his brain. The years unrolled like the faded page of a parchment strip. He found the name he sought.

Karl Hummel — Prussian spy! The brain of Agent “X” raced with excitement. He was gazing at a man who had played his part in the World War with ruthless cunning, the cunning of a person who believes the end justifies the means.

The Agent’s manner grew studied, calm. He turned back to the young woman again, the girl he guessed was Senator Dashman’s daughter. He started to ask a question, stopped. The front door was opening. Three men were entering the house.

“Doctor Stoll!” cried the girl. “Hurry! Something terrible has happened to dad! The house was robbed a little while ago — and now—”

A sob choked off the girl’s speech. She pointed to her father.

The foremost of the three men strode forward, a physician’s case in his hand, deep concern on his face. The Agent’s glance wandered past him, rested on the second man.

This man was thin, sharp featured, with eyes that showed penetrating intelligence. A small, carefully clipped mustache darkened his upper lip. His features were familiar to one who knew the city and its environs as Agent “X” did. Inspector Clyde of the Washington municipal police!

While Doctor Stoll began his examination of the senator, Inspector Clyde spoke to the senator’s daughter in the abrupt manner of a man accustomed to authority.

“Your servant reports there has been a robbery, Miss Dashman. The city, as you may know, is experiencing a wave of robberies. I came myself when I heard your father had been injured. If you will please give me the details.”

But the girl shook her head and turned from him. The doctor’s coming had relieved her of the need of keeping her emotions in check. She gave way to sobs and another young woman in the group stepped forward. This was the girl whose face was familiar to “X”—a girl who was a college chum of the Agent’s closest and dearest friend. She touched Inspector Clyde’s arm as the Agent looked on.

“Valerie’s in no condition to answer questions, inspector. The rest of us will tell you what you want to know. We were here, too.”

“And who are you?”

The girl’s answer was haughty. She stared at the inspector with chin held high.

“Suzanne Blackwell,” she said.

“Go ahead,” said Clyde gruffly. “I’m listening.”

“Sam, Lili, Otto, and I dropped in a little while ago to see Valerie. Her father was in his study here. The door was closed. Valerie sent Thomas, the butler, to tell the senator that guests had arrived. He didn’t answer Thomas’s knock. Valerie became uneasy because her father has been under a strain from overwork lately. She opened the door and found him as you see him now. The safe was open, papers scattered about. It seemed like a robbery — the window was open, too. That’s all we know.”

Inspector Clyde had a notebook in his hand. He spoke crisply: “These three friends of yours, Miss Blackwell. I haven’t had the pleasure of an introduction. Let’s get them straight. One at a time, please.”

AGENT “X” was paying close attention. The inspector’s brisk questioning was saving him trouble. Suzanne Blackwell’s next words startled him. She pointed toward the girl who stood between the two men by the door — a stunning, lithe-bodied brunette.

“Miss Lili Damora,” she said, “of New York, Budapest, and Washington.”

This was the girl Agent “X” had been asked to investigate, the black-haired beauty who had been seen in the company of Captain Nelson. She teetered self-consciously on high heels and patted her sleek coiffure with an affected gesture. She had luscious, pouty lips and the languorous air of a society belle.

Suzanne Blackwell indicated the two men next, giving the name of the dark one first, then the blond ex-spy.

“Mr. Sam Barkley, American sportsman, and Herr Otto von Helvig of the German Legation.”

Inspector Clyde wrote down these names and turned to the Agent.

“And you?”

“Captain Stewart Black — just arrived, inspector, to do a little questioning on my own account.”

In clipped sentences Inspector Clyde issued an order to the sergeant of detectives who had followed him in.

“Look around outside, Quane. See whether there’s anything on the lawn.”

The inspector himself walked across the study to the small safe that stood open, its papers strewn about. He hurled a question over his shoulder.

“What seems to be the matter, doctor?”

Doctor Stoll answered quickly. “A slight stroke, I should say. Some of you help me get him upstairs. Send for a trained nurse at once. Call this number.”

As Agent “X” stepped forward to assist, the front doorbell sounded again. There was a furious, impatient note in it this time. The Negro servant hurried to open it and two men burst into the hall.

One was short-legged, immaculately dressed, his round fat face pink with excitement. The other was taller, thinner, a gauntly saturnine look about him, a fanatical light in his eyes. Senators Josephus Cobb and Haden Eathborne.

Valerie Dashman, getting a grip on herself, went forward to meet them. Cobb spoke abruptly, words trembling from his lips.

“Rathborne and I have been arguing. We’ve come to have a talk with your father. We must see him at once, we—”

The senator’s voice ended in a fat wheeze. His eyes grew round with horror. The color slowly drained from his face and was replaced by the pallor of deep-rooted fear. For the Agent, Doctor Stoll, and Otto von Helvig were carrying the limp form of Senator Dashman out of his study.

Cobb’s eyes rested on his senatorial colleague’s sickly hued features. Then he gasped a sentence that seemed wrung from his lips.

“Good God — the ray!”

Inspector Clyde, following the procession, turned sudden, sharp eyes on Cobb.

“What was that you said, senator?”

Added fear leaped into Cobb’s eyes. He shook his head with abrupt emphasis.

“Nothing — nothing — I was only talking to myself. What on earth has happened here?”

“Robbery,” said Inspector Clyde. “And Senator Dashman has suffered a stroke.”

COBB stood speechless, swaying on his short legs as they carried Dashman upstairs. A faint sardonic smile showed on the face of Haden Rathborne. Suzanne Blackwell’s face had gone white.

The eyes of Agent “X” were tensely alive. Cross-currents of human drama had made the atmosphere of Dashman’s home electric. “X” hadn’t missed Cobb’s explosive mention of the ray.

As they laid the senator on his own bed, the Agent’s eyes rested on Dashman’s neck. A tiny red mark showed there. The skin around it was slightly swollen. The Agent pointed toward it.

“Look, doctor — what’s that?”

Doctor Stoll glanced down quickly, shook his head. “I don’t know,” he said. “I saw it. I’m wondering. It looks as though the senator had pricked himself. His pen perhaps.”

“Perhaps,” said the Agent, but his voice sounded skeptical. Then his eyes narrowed. A sudden horrible thought flashed into his mind.

That mark was part and parcel of the ghastly mystery, the folds of which seemed to be growing deeper and denser as he went along. He had noticed something else, and he hurried downstairs after they had laid Senator Dashman on his bed. The senator was in the doctor’s care now. All that could be done for him would be done.

“X” was thinking of the strange look of terror that had come over Suzanne Blackwell’s face when Senator Cobb had mentioned the ray.

Evidently she, too, had some knowledge of Browning’s creation.

She was putting on her hat and coat when Agent “X” reached the hallway below. He saw that her fingers were trembling. She was no longer the poised, self-confident girl she had been when he first entered. Cobb’s blurted utterance had shaken her for some reason.

Sam Barkley and Otto von Helvig hovered anxiously near her. Valerie Dashman was at her elbow.

“I must go home at once,” Suzanne was saying. “You’ll excuse me, won’t you, Valerie? I know your father will be all right. You won’t think I’m running away?”

“No — but why—”

“I can’t tell you now — but I feel — that I ought to go home.”

Sam Barkley laid his hand on her arm. “I’ll take you,” he said. “My car’s outside.”

Von Helvig intruded himself quickly. His tones were smooth but firm. There was a challenge in his eyes as he met those of Barkley.

“I was leaving anyway. I must get back to the legation. There is much work tonight. I will take Miss Blackwell with me, if she will be so kind.”

Barkley shrugged and stepped back. Von Helvig captured the girl’s arm. With a quick good night to the others, Suzanne Blackwell left. The Agent’s eyes followed the tall figure of Karl Hummel, alias “Otto von Helvig.” The man he had known as one of Europe’s most cunning spies. Here was a lead he could not neglect in his quest of the stolen plans. He must follow it, but not immediately. There was still Lili Damora.

He turned, looked about him. The woman from Budapest was in close confab with Senator Rathborne. It seemed to the Agent that she was using her charms upon him, attempting to dazzle the senator with her exotic beauty. Her lashes rose and fell coquettishly, sweeping her delicately tinted cheeks. Every gesture she made was for effect. The lithe balancing of her body on one graceful hip. The movements of her slim, carmine-tipped hands. Admiration gleamed in Rathborne’s narrow eyes. He seemed to lean over her predatorially.

Now was no time to question the woman — not with Senator Rathborne listening. Not with so many strange cross-currents in the air. He would see her alone, later. His eyes roved again.

SAM BARKLEY and Senator Cobb were standing together by the study doorway. The senator was mopping his fat face nervously. The pinkish flush of excitement had given way to a pallor that lingered. His glance swept the stairway up which they had so lately carried Dashman. He was waiting tremblingly for the doctor’s full report — waiting with a fear that “X” could well understand.

“X” walked up and introduced himself.

“I’m told,” he said, “that Captain John Bernard Nelson was murdered tonight. He was a friend of Senator Dashman’s. But perhaps you can tell me something, senator. What was the meeting in the State, War and Navy Building from which Nelson was returning when he was killed?”

Fear leaped into Cobb’s eyes. “I am not at liberty to speak,” he said quickly. “I know nothing about Captain Nelson. I never saw him before tonight.”

“Then you were at the meeting?”

“I did not say that!” Cobb gasped. “Really, captain! If there is a Government investigation into this matter and if I am called as a witness, I will answer questions at the proper time. Now—”

“I beg your pardon,” said Agent “X” suavely. “Since Senator Dashman has been unfortunate enough to have a stroke, it seems that my visit here tonight was timed badly.”

He excused himself, murmured a wish to Valerie Dashman that her father would soon recover, and left the house.

Once outside he moved quickly. The rain had stopped, but the sky was still overcast and fitful lightning flickered on the horizon. The Agent summoned a cruising cab and gave the address of Senator Blackwell’s house. Why had Suzanne Blackwell been so alarmed when Cobb had mentioned the ray? Did she fear an attack of like nature on her father? And what part was the former spy, Karl Hummel, playing in his new rule of embassy attaché?

These were the questions Agent “X” asked himself as the cab sped along. At the moment, there was no one in all Washington to help him. He had undertaken a tremendous task single-handed. And he seemed to be working in a confused and black night of impenetrable mystery.

He dismissed his cab a block from Blackwell’s home. It was farther along in the suburbs than Dashman’s residence had been. A wide lawn stretched around it. Wet shrubbery glistened on the lawn.

Agent “X” moved toward the house like a wraith. He had played his hand openly so far. Now he was going to play it secretively — look and listen before he made any further move. He climbed an iron fence, dropped onto the lawn. He moved across it through the wet grass toward the house where a flicker of light showed.

Fifty feet from the house Agent “X” paused with an abrupt tingling along his spine. Something had moved in the darkness, something that was fleeting, sinister. A sudden premonition of danger telegraphed itself to his ever-alert brain. With a motion that was instinctive he jerked his body to one side.

As he did so, something like a swift-winged insect whispered past his head. It struck the trunk of a tree with a soft spat, and stopped, ten feet away.

Agent “X” whirled, then fell to the ground. Out of the darkness of a mat of shrubbery, four figures leaped toward him. The sense of imminent, hideous danger warned him that he could only escape death by some quick ruse.

Chapter VI

HE lay still as the figures moved up. Their feet were uncannily silent on the grass. They walked like savages, bent forward, shoulders hunched. He caught a glimpse of the face of one in a shaft of light filtering from the street. That face was brown-skinned. Not negroid. The bones were too high, the lips too thin, the eyes too small and bright.

These, he felt sure, were the same men who had worn the green masks in the chamber where Saunders had been poisoned. These were the killers who had carried out a master murderer’s will.

The truth of this was verified a moment later. One of them spoke in the strange tongue that “X” had heard before and recognized. They closed in around him like wolves.

His stillness, his appearance of death, was all that saved him. Knives gleamed in the hands of two of the men. Another carried something else, a tiny, slender pipe, mysterious, sinister.

They muttered in their monosyllabic language. Two of them reached down, the ones with the knives. There was horrible purpose in the way their hands groped.

“X” hurled himself sidewise then with an abrupt movement that was timed to within a fraction of a second. A master of disguise and strategy, he could use physical force, too, when necessity dictated. His feet swept in a circle, knocking two of the killers to the ground — those with the knives. His powerful hand caught the ankles of the other two, hurling them off their feet.

There was something ghastly about their stoical silence. He had taken them by surprise, tricked them, by playing possum, but they made no noise as white men would have done. They showed the training, the discipline that an exacting master had instilled into them.

They sprang back toward “X.” For a moment one of their knives swept downward in a whistling arc.

The Agent struck then, lightning fast, with the tips of his fingers only. It was a strange blow, a thrust of his wrist forward. His hard finger tips jabbed the knifeman just under the armpit. The brown-skinned killer gave a grunt of pain. His knife slipped from his hand.

For a moment after the Agent had struck him he lay writhing in pain, his lips locked together. The second knifeman tripped over him. But the man with the strange pipe in his hands was stepping back. His hands were taut as talons. His eyes glittered with an evil, murderous light.

The Agent saw him raising the pipe to his lips. Here was death. The threat of the knives was as nothing compared to this new device. For “X” knew what that insectlike whisper past his head had been. He knew what it was that had struck the tree trunk.

With a movement like a wrestler, Agent “X” clutched the fallen knifeman, raised him above his head, and hurled him forward toward the other who held the pipe. There were steely muscles beneath “X’s” well-fitting uniform. He knew the secrets of leverage and suddenly applied strength. The man he had flung struck the feet of the other. Both rolled to the ground with a serpentlike hiss of breath.

A guttural order came from the lips of one who seemed to be their leader then. In an instant all four of the strange brown-skinned men were slinking away into the darkness. It was as though the night had swallowed them. One moment they were there. The next they had gone, and “X” could not hear even the sound of their feet. But, holding his head close to the ground, looking along it, he saw four shadows flitting across the iron fence that bordered the estate. A moment later he heard the sound of a motor starting up, heard it purr away into the night. Single-handed he had defeated them, but he did not fool himself. Sooner or later he was destined to meet them and their devilish master again.

THE Agent rose to his feet. The elbows and knees of his uniform were wet and muddy. Mud smeared his sides and back. But he hardly noticed it. He moved forward for a moment, turned on the beam of a miniature flashlight with a bulb hardly bigger than a grain of wheat. He pointed it toward the ground, stopped and picked something up.

In his hand was a featherweight pipette — a hollow reed, open at both ends — seemingly harmless. It had dropped from the brown-skinned man’s fingers when he had fallen. One end of it had been stepped on and crushed. It was useless now, but the Agent knew it had been more deadly than the fanged jaws of a snake. It was a blowpipe, a savage assassin’s weapon, simple as it was terrible.

He walked back to the spot where he had been when the strange whisper sounded so close to his head. Again his light flashed on. Sticking in the trunk of a tree was a tiny dart, a, brilliant green feather at one end, a bone point at the other with a black, gummy substance adhering to its surface.

He drew it out, broke a section of the blowpipe as a guard against the deadly point, and put it in his pocket. His mind flashed back to that small mark on Senator Dashman’s neck. Here was the answer. It had not been the paralyzing ray, but something almost as sinister. Two horrors hung over Washington: the threat of one still unleashed; and the real, ever-present menace of a band of hideous poisoners whose motives were veiled in mystery.

Eyes harsh as steel points, Agent “X” moved on across the lawn toward the house. This was what he had come for. The four brown-skinned killers had delayed him, but had not turned him from his course.

There was a light in the room that seemed to be the library. The rest of the house, save for the servant’s quarters, was dark.

Agent “X” again took his chromium tools from his pocket. He had not forgotten the words of the man who had spoken to him through the desk — the man who had summoned him to Washington. “Your task is greater than the mere pursuit of a murderer — a thousand times greater.”

The threat of murder was a side issue. He was here to battle an unseen threat to a nation.

With swift, tense movements he came close to the house. A light showed over the vestibule of the front door. He went to a side entrance where no light showed in or out.

Silently, deftly, utilizing all the skill he possessed, he used his steel implement to pick the lock and enter the house. He found himself in a narrow hall that seemed for the use of servants alone. He moved along it, remembering where the lighted library was. He heard servant’s voices in a room at his left. He passed through a door at his right, the dining room. He crossed a hall, saw the library ahead. The door of that was ajar. Voices came from behind it. Agent “X” crept close.

The voices came plainly now. Risking the possibility of being seen he moved closer still. The door of a writing room showed near by. He would duck into that if a servant should come.

There were three persons in the library — Suzanne Blackwell, a young man, and the senator, her father. Von Helvig was not there. He had apparently taken Suzanne only as far as the door.

There was tense drama in this expensively appointed room. The Agent’s eyes snapped. The girl, Suzanne, was speaking, her face still white, her slim hands clenched. She was talking fiercely to her father.

“It was the ray, I tell you,” she was saying. “The ray you told us about. Senator Cobb said so. I heard him. If you had been there to see Senator Dashman you would believe me. It was horrible. I remembered what you had said and I was afraid — for you.”

THE ruddy face of Senator Blackwell was contorted. A cigar was clamped in his mouth. He was pacing the room. There was a strange, haunted look in his eyes. His daughter’s words seemed to be affecting him strangely, but he spoke with explosive emphasis.

“What you say is impossible! Do you hear? I should never have told you about the ray. It put silly ideas into your head. The plans of it only were stolen — just a few hours ago.”

“They were stolen, then?”

“Yes — but you mustn’t breathe a word of it to anyone. No hint of it must reach the papers.”

The young man in the room spoke suddenly. Agent “X” had been watching him. He looked like Suzanne in feature, but he hadn’t her spirit or haughtiness. There was weakness in his mouth, lines of dissipation around his eyes. His complexion was bad. The muscles of his face were twitching. His hands shook, and the tones of his voice had an hysterical quaver.

“They’ll get us all,” he said shrilly.

The senator turned on him fiercely. “You’re a fool, Ferris. As a son you disgrace me. If you can’t talk sense, shut up. Don’t frighten your sister more than she is. I want both of you to forget this thing. You’re going away, Ferris — back to the sanatorium for another treatment.”

It was painful to see the twitching of the young man’s face now. To the eyes of Agent “X” the evidence was plain, Ferris Blackwell was a drug addict of some sort. Here was tragedy in a high place.

“I can’t go yet,” said Ferris. “Not until I’ve seen someone!”

The senator answered sternly. “Doctor Claude says that one more treatment is necessary. I spoke to him today. He’s coming for you — and you are going with him tonight.”

The eyes of the two men clashed strangely. Ferris Blackwell’s lips began quivering violently. Then he cried out and hunched back as though trying to escape his father’s penetrating stare. Suzanne Blackwell suddenly straightened her shoulders.

“I’m sorry, Dad. I’ll buck up. It’s bad enough to have one weakling in the family. I was scared tonight — that’s all. I left right away after Senator Cobb mentioned the ray. Otto von Helvig brought me home.”

“You didn’t tell him your fears?”

“No.”

“Well don’t. I don’t like him, Suzanne. He asks too many questions. He’s the last person in the world who should hear about any of this.”

“Why?”

“Because he works for a foreign government, and because I don’t trust him as an individual. Stick to Barkley — if you must have a man hanging around. He may be a loafer — but he’s harmless.”

“And you don’t think Otto is?”

“No — I tell you I don’t trust him.”

Senator Blackwell jerked his watch from his pocket.

“It’s ten-thirty now,” he said. “Doctor Claude will be here any minute. Get your things packed, Ferris. You’ve got to go with him. Try to behave like a man.”

Agent “X” withdrew quietly. He had heard enough. He was determined now to trace Otto von Helvig and see whether this man was still engaged in espionage activities. If so, the stolen blueprints of Browning’s hideous mechanism might have passed through his hands.

Chapter VII

THE eyes of the Secret Agent were gleamingly bright. A desperate plan had occurred to him. Not to confront von Helvig at the legation. That would be futile. Disguised, he could interview the man. But there was an infinitely better way.

He would get at the very heart of Washington’s espionage activities, find the center of that spider web of spy work which is spun about every capital in the world, even Washington. Along its threads would travel whatever whispers there were concerning von Helvig and Lili Damora.

The Agent deliberated a moment, frowning. There was no one in Washington to help him; no one upon whom he could depend for information concerning the movements of the five who had sat on the senatorial committee.

Beneath the peaceful surface life of Washington lay a dark underworld of espionage, a dank, unwholesome labyrinth. While he investigated this, he needed someone to contact the stratum above. The future safety of America hinged on the return of the Browning plans.

Yet in all the world there was only one person who could help him. Only one whom he could completely trust. That one was Betty Dale. Blonde and lovely, daughter of a police captain who had fallen victim to underworld bullets, Betty hated criminals as much as “X” did.

She was a lady of the press now, a society reporter, forging ahead by her own hard efforts. She would come to Washington if he asked her to. The paper would give her leave.

It would be a simple matter, too, for her to move in the very circles “X” wanted watched. For Betty had invested her father’s life insurance money in a college education — and at college Suzanne Blackwell had been her roommate. When in Washington Betty always stayed with Suzanne. There was nothing more natural than that she should come to Washington now, to cover for her paper the ball that Senator Marvin Foulette was giving tomorrow night. A wire from “X” would bring her.

But Agent “X” had qualms. What right had he to ask her? The theft of the plans had brought horrible forces into play. Was he justified in risking Betty’s safety in the slightest degree?

It was minutes before he could decide this question. He knew that if she ever found he had needed her and not called her, she would be hurt. She’d asked him to promise once that he would always tell her when she could be of use to him. Often in the past she had helped him. At the times when he took money from crooks she distributed it for him among the helpless victims of crime; among the innocent children of men sent to prison; among widows left by assassin’s bullets.

And, with America itself menaced, she would be eager to take any risk. He finally made his decision. On the way to his hideout Agent “X” sent a carefully worded telegram to Betty. It would bring her by plane the next day. He instructed her to proceed directly to Suzanne’s house, not letting Suzanne know that her visit had any purpose except to cover Senator Foulette’s ball.

At his hideout “X” swiftly examined the tiny dart which had so nearly imbedded its point in his flesh. He scraped the black, gummy substance from the tip and sniffed at it. Then he took a small box from the false bottom of his suitcase. It held a compact chemical outfit — miniature vials of acids for chemical tests, a tiny collapsible retort for making distillations.

He put the substance from the dart in a test tube a quarter inch in diameter and used the flame of his cigar lighter in lieu of a Bunsen burner.

TEN MINUTES of analysis confirmed his suspicions. The gum on the dart was poisonous black resin from the deadly Rengas tree, known also as Singapore mahogany. Agent “X’s” eyes reflected hot pin points of light as his mind flashed back to that tiny mark on Senator Dashman’s neck, his strangely paralyzed condition, his stertorous breathing.

The brown-skinned men spoke a Malayan dialect. The Rengas tree was found commonly in the Malay peninsula. This upheld his belief that the murderous Green Mask headed a band of Malay poisoners. The blinding powder loosed in Saunders’ car was probably Malay. So also was the Kep-shak torture which had ended Saunders’ life.

Agent “X” replaced his miniature laboratory, and shed the army captain’s uniform. He stripped the makeup from his face; with swift precision began to create a new disguise. Beneath his skillful fingers an inconspicuous-looking young man emerged — a man with a smooth-shaven face and sandy hair; a man who carried the cards of H. Martin, Associated Press reporter. He had credentials, travelers’ checks.

He left his hideout and went to a “drive-yourself” garage, hired a smart roadster with a roomy compartment in the rumble seat. He sped along the night-shrouded streets of Washington, eyes bleakly alert.

It was nearly midnight now. A chill drizzle still fell. Lowering clouds hung low over the city. Danger seemed to lurk in the darkness.

He followed Massachusetts Avenue to Stanton Square. He cut into Maryland Avenue, circled the Capitol grounds, then headed down Delaware Avenue toward that point of land bordered by Washington Channel on one side and Anacostia River on the other.

Ahead of him was the Army War College, but he stopped before he reached it, turning into a dark, nondescript side street. Here, within a half-mile of the War College, was a place known to “X” as a hotbed of espionage. Perhaps spies chose this spot because it was close to some of America’s military secrets, past and present. Perhaps it was to keep an eye on the men at Uncle Sam’s fighting college.

Agent “X” did not know. But he knew that at a certain address in this dark, badly lighted street was a clearing house for spy information. Here a sinister personage conducted a sinister traffic. Here secrets for which men risked their lives and women risked their honor were bought and sold. Here dwelt a man who was a veteran operative of espionage.

Agent “X” had long known of his existence. So had men of the D.C.I., but they did not know his address and “X” did. He had long hoped that this knowledge might prove useful. Now the time had come to test it.

He parked his roadster a block away, proceeding along the dark street as silently as a shadow. The house he sought was a wooden, three-story affair. He saw it looming darkly, no lights in its windows, something unprepossessing about its misshapen lines.

Its infamous occupant had apparently gone to bed. But one could never be sure — not with the man who used the business name of Michael Renfew. He was as cunning as a fox, as spineless as a rabbit, except—

Agent “X” knew Renfew’s character. The man was an espionage merchant. His own active days were over. He was a coward at heart, but a sly, sneaking jackal of a man; and a man still to be feared.

The Agent didn’t go to the front door. He went to the rear of the house, creeping along its side, moving like a wraith. At the rear door he took out his tool kit again. Never had he been so careful as now. A man like Renfew would have ears that would detect any sound. His dangerous work would make him fear for his life. He would take means to safeguard it.

The Agent, before he opened the rear door, took a small metal disc from his pocket. He drew from its side a ribbon of gleaming copper that was like a measuring tape. But it had no numbers on it. It served another purpose.

He thrust one end of it in the moist, rain-wet earth. With a thin tool like a knife blade he probed cautiously around the door’s edge till he heard the faint scrape of metal. There he wedged the knife blade. He attached his metal disc to it, and opened the door.

By doing this he had disconnected an ingenious burglar alarm, which operated on a broken circuit when the door was open. Agent “X” had seen to it that the circuit remained unbroken.

He entered the house and closed the door after him. He took off his shoes, laid them on the floor, and moved forward on his stocking feet.

Was it possible that Michael Renfew was not at home? Agent “X” planned to see — and wait for him if he wasn’t.

A second door he came to was closed. With the caution of a man whose dangerous life had taught him eternal vigilance, Agent “X” explored this also.

HE found two tiny electric wires, hardly larger than threads, running along the frame. The door had an alarm system, too. He scraped the insulation from the wires, connected them with a small piece from his own pocket, and opened this door. He was convinced now that the spy was at home.

A flight of stairs that had a tendency to creak gave him trouble. Once he paused, thinking he heard movement above. Then he continued upward, stepping on the sides of the stair boards to prevent movement.

He came at last to the door of a bedroom, closed like the others. It was many minutes before he found means to open it, found the location of the last electric alarm. There wasn’t a burglar alive who could have entered that house without waking the tenant. But Secret Agent “X” was no burglar.

An old-fashioned four-poster bed was in the room. A man was sleeping in it. So silently had the Agent approached, so trustful was the man of his alarm system that the Agent crept to the bed and bent over the sleeper and still the man slept on. The Agent clicked on his tiny flashlight, then leaned forward to wake the sleeper.

As he did so Renfew stirred. He was a gaunt, wizened man with a bald head and a face as wrinkled and leathery as a turkey buzzard’s. He opened his little eyes, gave a sudden scream of fear.

Quick as a striking snake his hand reached out toward a cord beside his bed. He yanked it, and in the same instant Agent “X” leaped forward, sprawling across the bed. As he did so the floor beside the bed where he had been standing a second before dropped away. A trapdoor fell downward, a yawning black hole leading all the way to the cellar opened up. How many people visiting Renfew had taken this terrible plunge?

“X” grasped the wrinkled spy’s body, held him fast by the arms, while his eyes glared into Renfew’s.

The spy screamed again, and the Agent shook him as a terrier would shake a rat.

“Silence,” he ordered, and his strangely compelling voice seemed to affect Renfew like a blow. The spy lay back gasping.

“Who are you,” he croaked, at last. “Don’t kill me. I have nothing!”

The Agent had drawn a gun from his pocket. It was a gun that fired only a small charge of anesthetizing gas, but Renfew didn’t know that. The muzzle of the gun was pressed against his chest.

“Get up,” said the Agent, “and get dressed.”

“Who are you? What do you want?” the man repeated.

“Never mind! Get up!”

“X” moved across the bed to the other side, avoiding the black pit left by the trapdoor. He kept his eyes fixed on Renfew, alert for tricks. He kept his gun against the spy’s body. He pulled the cord of a small electric bulb, flooding the room with light.

Renfew stared at him with glittering eyes. His face showed no recognition. The Agent’s disguise was a perfect blind. He took his press card from his pocket, held it before Renfew’s face.

“A newspaper reporter,” the spy gasped. Then his eyes became crafty. “Perhaps we can make a deal. There is no need for violence.”

Remembering the trapdoor, “X’s” eyes grew steel hard. “A broken neck is rather violent,” he said harshly.

“I thought you were a burglar,” said Renfew.

“Dress and come with me,” was the Agent’s order.

“You are a fraud,” screamed Renfew suddenly. “You are not a press reporter. You are going to kill me.”

“Not if you obey my orders,” said the Agent. “Otherwise—” He gave the spy a jab with the muzzle of his gun.

WITH trembling arms Renfew began to dress. There was something inhuman about the dryness of his face. He had the complexion of a mummy, but the eyes were wickedly alive. “X” wished he could turn the man over to the police. But that could not be done now. He must use Renfew’s establishment and Renfew’s reputation.

When the spy had dressed, “X” motioned toward the door.

“I am leaving,” he said. “And you are coming with me. Make any move to escape and—” Again he gave the man a vicious jab with his gun.

Keeping his light switched on, he pushed Renfew ahead of him down the dark stairs. The man’s voice shook with terror as he asked a question.

“The alarms — how did you get through them?” His eyes rolled back toward Agent “X.” He looked with awe into the steady, steely gaze of the Agent. “X” did not reply and Renfew seemed to wilt, sensing that he was in the power of a man who possessed supernatural powers.

“X” pushed Renfew out into the night, keeping a grip on his arm. He held the muzzle of his gun close as they moved along the street. When he came to the spot where his car was parked he made Renfew get into it. In silence he drove off.

The spy’s face had gone a sickly white now. The paleness of his complexion, overlaid with its network of wrinkles, was hideous. He kept glancing sidewise at “X.”

Agent “X” drove quickly, plunging along the dark quiet streets. The city seemed to have gone to bed. Once the whistle of a patrolling cop shrilled at “X” to slow down, but he sped on.

Not until he came to his hideout did he stop. Then he took a firm grip on Renfew’s arm. He pressed his gas gun close to the left side of Renfew’s body.

“Quiet!” he warned.

Renfew moved forward shivering.

“X” had a key. He entered and went into his small furnished apartment without anyone seeing them. Renfew stood trembling, his eyes darting about, as though not knowing what strange thing to suspect.

“Sit down,” said “X” suddenly, and pushed Renfew into a chair. He turned then and locked the door. The spy sat shaking, looking up at him like a cornered rat.

“I know all about your work,” said “X.” “I know that you sell Government secrets as other men sell merchandise. I know that you are loyal to no country in the world, but give what you have to the highest bidder.”

The Agent stopped speaking, took a wallet from his pocket. From it he drew a huge sheaf of bills. There were notes written in four numerals on the top, many others in three. Renfew’s eyes bulged. Greed took the place of fear. He licked his lips, then smiled.

“Perhaps we can make a deal yet,” he said.

“Perhaps,” said the Agent. “What great secret was stolen from America within the past twenty-four hours?”

Renfew was silent a moment, his eyes stabbing the Agent’s. He began to fence.

“Many rumors have come to me.”

“One thing — more important than any,” said “X.”

“Perhaps the building of the new D10 submarines,” said Renfew. “I have been offered—”

“No,” said “X” harshly. He held a thousand-dollar bill forward, watching Renfew’s face fixedly.

“I’ll give you this as a down payment if you tell me what I want to know.”

Renfew’s eyes stared avidly at the bill. His lips moved again.

“Perhaps the secret commercial treaty with—”

“X” stuffed the bill in his pocket “You do not know,” he said. He was convinced of it. News of the stolen Browning plans hadn’t reached Renfew’s ears as yet.

HE did not question Renfew further. The man’s secret records would give him the leads he sought. He looked at Renfew fixedly for a moment. The spy’s face began to pale again, losing the color that had come back at the sight of money. He sensed something speculative and coldly impersonal in “X’s” attitude.

“What you going to do?” he cried.

“This!” said “X”—and before Renfew could move he raised his gun and pulled the trigger. The spy opened his mouth to give a piercing scream, but a cloud of gas from the gun’s muzzle filled his throat, choked him.

One gurgling whisper came from his lips, then slowly he slumped forward and fell to the floor. He was not dead, merely knocked out, and he would remain so for many minutes.

The Agent looked at his watch. It was nearly twelve-thirty.

He wanted to make sure that Renfew stayed unconscious for a good while to come. He could take no chances with the spy now. A method of getting him out of the country had occurred to the Agent. But there was no time to effect it. He went to his suitcase, opened the false bottom and took out a minute hypo needle. Expertly he jabbed this into Renfew’s arm. For twenty-four hours, unless the Agent chose to wake him sooner, Renfew would remain unknowing.

Next the Agent propped Renfew back up in the chair and studied him. For long moments he looked at the man from every angle. Then he got his make-up materials and began to work on his own features. This was his object in capturing the spy. By stepping into Renfew’s shoes he hoped to gain information that could be gotten in no other way. The disguise he now undertook was in many ways the most difficult he had assumed for many months. Small strips of the transparent adhesive were necessary to simulate Renfew’s wrinkles. The Agent plastered his own brown hair down with a special liquid that evaporated on contact with the air.

Before it had a chance to disappear, and while his hair was still close to his scalp, he slipped a rubber cap over his head, giving an impression of baldness. He added plastic material around the edges, smoothed it out — and when he had finished, Renfew’s double seemed to be standing in the room.

“X” went through the spy’s pockets carefully, took out all papers and keys that might be helpful, and carried Renfew’s inert body to a big clothes closet. He had had an eye to this in selecting the apartment. There was a wide crack under the door. Renfew would not suffocate. “X” put him in and locked the door.

Then he went quickly out into the street again and climbed into his roadster. He made the trip back to the dark section of town where Renfew lived in fifteen minutes.

He parked his car, walked forward, and quietly entered the spy’s three-story house.

His first act was to return to Renfew’s bedroom and close the trapdoor. A breath of dank, moldy air rose upward from the cellar as he pulled the door shut. He fastened it and carefully arranged the cord by the bed again.

Then he searched around the room till he found an old safe concealed inside a big desk. At the end of ten minutes the Agent had opened this. With eyes intent he began going through the spy’s private papers.

Most of them were in code, but he remembered the tattered, well-worn book he had taken from Renfew’s pocket. He would have been able to decipher the code without it, but time was an important element.

He opened the book, found the code key, and began reading the papers.

Here were brief reports of espionage deals that would have shocked the State Department. Records of military secrets being bartered, records of the bribery of public officials. Entries that hinted at dark, unspeakable things done to gain information which could be sold.

Then Agent “X” suddenly raised his head. He listened a moment, thrust the papers back into the safe and closed it.

The faint jingle of a bell had sounded eerily in the still house. Someone was at the front door.

Chapter VIII

THE bell’s note was repeated as he tiptoed down the dark stairs. He might be facing a bad situation. This might be one of Renfew’s friends. Would his disguise work?

Strange echoes were still sounding through the old house as he reached the front door. Small leaded windows were set in its side frame — more of Renfew’s precautionary measures.

Agent “X” used one of them now. At first he could see nothing. Then his eyes got used to the gloom of the street outside. It was at least brighter than the room he was in. Light from a distant pole lamp filtered along the pavement.

A man was standing outside. He was hunched over. His collar was turned up. His hat pulled down. Agent “X” caught a glimpse of his profile. He had never to his knowledge seen the man before. The man was just about to turn away when “X” opened the door. He started violently, peered forward.

“I was afraid you weren’t in, guv’nor!” the man said.

His accent seemed to indicate cockney extraction.

“A fine time to wake a man up,” said Agent “X,” imitating Renfew’s cracked voice. “What do you want?”

“I’d like a few words with you, Mr. Renfew.”

The man stared behind him along the street. There was a look of uneasiness in his squinted eyes. When “X” told him to come in, he entered the house with the quick, slinking gait of a furtive animal.

“Now what is it?” said “X.” He turned on his little light. It was pointed straight into the man’s face. In his other hand was his gas gun.

“It’s all right,” said the stranger hoarsely. “You ain’t never seen me before, guv’nor — but I’ve heard of you. Don’t get excited.”

“What’s your name?”

“It ain’t important, guv’nor — if you don’t mind — I’ll — I’ll tell you later — after we’ve had a talk.”

“What is it you want of me?”

The man came closer. There was an odd, hungry look in his eyes. “We might as well play square with each other,” he said. “You buy — things. I know that. I ain’t no fool, and I’ve got something to sell — information you might call it.”

“Information?”

“Yes.”

“Follow me,” said Agent “X.”

He led the stranger up the stairway and to a room on the second floor which had served as Renfew’s office. He pulled down the shade, turned on a light, and seated the stranger before a cracked desk. He took a seat behind the desk himself.

“Now what is it?” The Agent’s burning eyes were watching the stranger’s face. The man was at least not dangerous. But he was furtive, tricky-looking — a type common no doubt in this house of espionage.

“Well, guv’nor,” the man said, “there was something stolen tonight right here in Washington — something important enough so that the bloke that stole it killed the bloke that had it. And maybe if I wanted to I could tell the Government where to find it. I ain’t saying I could, but maybe I could.”

The man stared at Agent “X,” licking greedy lips now. The hungry light in his eyes was itching avarice.

“I’m a poor man,” the stranger continued. “I work hard and don’t get nowhere. If it just happens that I get information that somebody else might buy, there ain’t no harm in my selling it, is there?”

“No,” said the Agent. He tried to keep back the excitement that he felt. Here was a development apparently more quick and fortunate than he had dared hope.

“It ought to be worth a lot of dough to someone,” the man said. “Thousands.”

His thin fingers moved as though he were already enjoying the feel of many bank notes. “I could leave this bloomin’ country and go back where I came from,” he added.

“Just what is this thing that was stolen?” said the Agent. “If you’ll tell me what it is perhaps I can give you a better idea of its worth.”

THE man leaned forward. His voice was a hoarse, dramatic croak. “A thing that could turn a whole army into stiffs in a second,” he said. “A thing so ’orrible that ’alf the countries in the world would like to get it—’cause they love each other so much!” A shrill cackle of laughter came to his lips. He spread his fingers, struck his hands together. “They’d go down like that — the sojers — if you turned this thing on ’em. An’ the country that gets it can wipe out the rest.”

“You are English,” said “X.” “I should think you’d want to let your country have this thing.” He was baiting the man now, seeing what else he could learn. The man shook his head.

“England ain’t never treated me no better than America. I’m like you. I’ll sell to any bloke who has the price. An’ I didn’t say I could get this thing — I said I knew maybe where it could be got.”

“Did a man named Browning invent it?” asked the Agent suddenly.

The man recoiled, fear veiling his eyes. Then he cackled again. “You old fox, Mister Renfew! You’re smarter than I thought — pretending like you didn’t know. Yes, it was a bloke named Browning. You know about it then. You know how much it’s worth. You—”

The man stopped speaking suddenly, turned his head toward the window.

“Did you hear anything?” he said.

“No,” said the Agent.

“I thought I did. Pull that shade down — all the way. There’s a crack! I thought some bloke followed me here.”

The Agent rose, walked to the window, drew the shade farther down. He saw that the stranger’s face was white with fear.

“Tell me your name,” the Agent said calmly, “and perhaps we can do business. I deal in the sort of thing you have to sell. I have wealthy customers.”

“No,” said the man, “I can’t tell you my name — not now. I’m hired by a bloke who’s a big gun in this city, an’ the country, too. I work fer him, you understand. I happened to hear him make a threat against the bloke who was killed tonight — the bloke that had what was stolen. When the bloke was killed it wasn’t ’ard to figure who killed him. It wasn’t ’ard either to figure who ’ad the thing that was stolen.”

“What’s your employer’s name?”

A crafty look came into the stranger’s eyes. “Say, listen — not too fast!”

The Agent extracted two thousand-dollar bills from his wallet. He flung them down on the desk.

“Maybe this will make it easier to talk.”

The man swallowed twice. He stared at the money. His hands twitched as though he could hardly contain himself. His voice was a husk when he spoke.

“I can’t tell you nothin’ now,” he said. “It’s all got to be arranged businesslike. I just wanted to find out — whether you was in the market. You are — I can see that. I got to have papers drawn up — a lawyer an’ everything — to see I don’t get into trouble.”

“Right!” said the Agent. He saw that the man wasn’t going to talk. He shoved one of the thousand-dollar bills forward. “Take that,” he said, “just as a mark of good will — and as a sort of option. Don’t tell anybody else what you’ve told me, will you?”

The man grabbed the bill, fingered it lovingly.

“No, sir,” he said. “It’ll stay between you an’ me. But I gotta have a lot more of these, an’ everything’s got to be businesslike, the way I said.”

“When will I see you again?”

“Tomorrow night,” the man said.

The Agent nodded. He rose and showed the man downstairs.

“Tomorrow night,” he said softly, then opened the door and the strange, furtive-faced man slipped into the darkness.

Agent “X” knew he would be back — unless something intervened. It was this possibility that made the Agent move quickly after his visitor had gone. Too many sinister forces were in the wind to take any chance. Too many unscrupulous people wanted the information the stranger had to sell. The Agent dared not wait.

Snatching a hat and coat, he ran to the back of the house, slipped out the rear door. Ten seconds after the man had left the front, Agent “X” was on his trail. The man did not know it. He did not know that one of the most masterly shadowers in the world was following him. He used several common ruses to throw off pursuit. He dodged around corners, kept to the dark side of the streets. But Agent “X” did not lose him.

The man got into a small car, drove off. The red tail-light of his auto bobbed up the street. In less than a minute the Agent was following in the fast roadster that he had hired.

It was a long chase, through the night-darkened streets, then out into the still darker suburbs.

ON the highway, almost deserted now, Agent “X” turned off his headlights. For nearly a mile he followed the car ahead, keeping on the road by the dim light reflected from the rain-wet macadam. Trees and fields began to flash beside the road at last. A golf course, silent and deserted, stretched away under the night sky. The road began to cut through dense woods. Rich men’s estates formed little oases of green turf in this forest.

Then “X” saw the car ahead draw to the side of the road, turn and jounce into the bushes. Its red tail-light disappeared, winking off suddenly.

“X” stopped his own car. He left it parked far off the road, sprang out and walked ahead. A distant boom of thunder sounded hollowly across the still, wet woods. He stopped when he came near the spot where the stranger had parked. He listened and could hear the faint sound of footsteps, the rustle of small bushes as someone moved away. The man had struck off through the woods.

“X” entered them cautiously. Shadowing would be difficult now. The woods were black. He could not see the man. He was on unfamiliar territory.

Stooping, he felt the ground with cautious, exploring fingers. The bushes were denser in spots. Less so in others. He continued to feel; made a discovery. A narrow path began here.

This helped. He walked along, feeling his way. Again he stopped. The man’s footsteps were softer now. They grew fainter still and died, as the Agent listened. The man evidently knew his way along this path. The Agent risked flashing his tiny light. The denseness of the woods would hide its glow. He made sure of the path he was on.

For the space of fifteen minutes he lost all sight and sound of the man ahead. But he made sure he was following the path. He was confident where the man was going. A chill dampness came out of the wet woods around him. Once a frightened bird gave a shrill cry. Once a small animal, a squirrel perhaps, skittered away among wet leaves. The Agent continued his way.

Then at last he saw a light ahead. He moved on along the path, and the light became two — the windows of a small house. Beyond them he could see another faint light which seemed to be a larger house. He was approaching one of the rich men’s estates from the rear.

But, as he neared the lights he had first seen, the Agent suddenly paused. A scream cut through the stillness of the damp, night woods. It was a fearful scream that sent prickles along “X’s” back. It held fright, horror. And, as he moved ahead again, running now, every muscle tense, the screaming mounted into a cry of sheer agony that beat upon the eardrums intolerably.

The Agent raced toward the spot. Fearful and shrill as the scream was, he sensed that it was muffled by walls. It had come from inside the cottage where the lights showed. As he neared this the screaming died to a ghastly gurgle, then faded away entirely.

The Agent burst through a patch of shrubbery that marked the path’s end. For a moment he paused, almost tripped.

In the light that flared from the windows of the cottage he had caught sight of a face against a background of wet tree trunks. It was turned toward him, eyes glittering. It was the horrible, green-masked face of the man who had murdered Saunders.

Chapter IX

THE face vanished before “X” could move. There was no sound in the darkness. The face and its owner seemed to melt into the woods and be swallowed up by tree trunks. Any attempt at pursuit in that Stygian blackness would be futile — and fatal. “X” sped ahead and jerked open the door of the cottage. Perhaps he would be in time.

But he saw in his first horrified glance that he wasn’t. A ghastly sight met his eyes.

A man was stretched out on the floor. His coat, shirt and undershirt had been ripped open. Livid scratches made a network of crimson lines across the bare skin of his chest. Grayish powder showed around the edges of the lines. The man’s face was contorted into a hideous mask of agony. But, distorted as it was, the Agent recognized it.

This was the same man who had come to Renfew’s place with a secret to sell — and the man was dead.

The brutal Kep-shak torture had been used. A large amount of the death-flowers’ pollen had been rubbed into his wounds. So much that the man had died after a few moments of excruciating agony. But not before, “X” guessed, he had babbled his secret to Green Mask. Once again Green Mask had gotten ahead of “X,” wrung a secret from a dying man’s lips.

Cursing harshly, fists clenched, Agent “X” stood for a moment staring down. The menace of Browning’s stolen plans was bad enough without having the added horror of this green-masked killer ever present. The murderer’s move tonight convinced “X” of one thing. Green Mask did not have the stolen plans in his possession. He, too, was after them. It was a race between himself and Agent “X.” A race that had become a titanic struggle.

The Agent looked quickly around the room. There was nothing here of interest. Even the man’s name was not important now. He would never satisfy his greed to sell the information he had obtained. He was a mercenary, disloyal rogue, but he did not deserve such a death as this. No human being did. Again the Agent’s curse was like a pledge.

He turned toward the door of the cottage, opened it cautiously. The night outside seemed dark. But when he stepped across the threshold, a harsh voice spoke close to his ear.

“Hands up! Don’t move, fellah — or I’ll blow your damned head off!”

Slowly, stiffly, the Agent raised his hands. A man with a double-barreled shotgun was moving around the edge of the cottage. The gun was pointed straight at “X’s” head. He knew what a load of buckshot would do at such close range. He waited, hands held stiffly aloft, and another man followed the first. This second man was clad in a chauffeur’s uniform. The first one wore overalls and looked like a gardener.

“We seen you slip into the cottage,” the man with the gun said. “We heard Peters hollerin’. What’s goin’ on here?”

“Look and see,” said “X” quietly.

The man in the chauffeur’s uniform did so, while the other held the gun unwaveringly on “X.” A hoarse, horrified curse came from the open door of the cottage.

“Good God! — Peters has been murdered!”

“Murdered!” the gardener’s eyes glinted. “We got the killer here, Jake. Hold the gun on him while I take a look.”

The chauffeur came out, trembling violently. The whites of his eyes were showing. His lips were blue. When he took the gun, his hands shook so that “X” thought he might pull the trigger accidentally.

The gardener went in. He, too, swore and came out like a man who has seen a ghost.

“Tortured,” he said. “This devil scratched him up first and killed him afterwards.”

He jerked the gun from the chauffeur’s hands, jabbed its heavy muzzle against “X’s” body.

“Who are you? What did you do that to Peters for?”

Agent “X” spoke quietly again.

“I didn’t. It was another man — a man in a green mask!”

The gardener’s voice was a disbelieving snarl. “A likely story. Get going, you buzzard. We’ll wake the senator up — an’ tell him about this. We’ll turn you over to the cops.”

The Agent’s eyes burned like fire. He said nothing more — and he did not try to break away. He wanted to learn whose estate this was — which senator it belonged to. The dead man, Peters, had said that he worked for a “big gun.” In a moment “X” would meet the man — the person whom Peters thought had stolen the plans.

The gardener and the chauffeur conducted “X” along a path to the big house which loomed in the trees ahead. A light was burning in one of the top-floor windows.

“The senator’s still up, Jake,” said the gardener. “Run and get him down. Then open the back door. I’ll take this killer in.”

He held the shotgun close as the chauffeur sped off.

“I’d like to pull the trigger,” he snarled. “I’d like to blow you in two after what you did to Peters.”

TWO minutes passed. Lights flashed in the lower floor of the house. The kitchen door swung open.

“Bring him in. The senator’s down,” the chauffeur called out.

The gardener, still prodding “X” with the gun, marched him into the house and through the kitchen.

In a front room, a gaunt, saturnine-looking man in a dressing gown and slippers was waiting. Agent “X” recognized him at once. Senator Haden Rathborne.

The man’s deep-sunken eyes were burning. His thin lips were twisted. He fixed his piercing gaze on “X.”

“Who are you? What’s the meaning of this? They tell me you murdered Peters.”

Agent “X” was silent, and Senator Rathborne strode across the floor and came close.

“Keep the gun on him, Benstead. Shoot if he makes a move.”

Chin thrust forward, eyes glaring, Rathborne seemed to be trying to bore into “X’s” very soul. Agent “X” returned his stare calmly. He in turn was sizing up the senator. It was a dark rumor he had heard about Rathborne. Peters had said that the senator had threatened Captain Nelson’s life. But was it possible that Peters had made some mistake?

“Speak up,” said Rathborne. “Who are you?”

Still “X” was silent, and Rathborne gave an abrupt, harsh order.

“Search him, Jake.”

The chauffeur went through “X’s” pockets, brought out a wallet. But there was no name in it. He shook his head and passed it to the senator. Rathborne cursed angrily.

“I never saw him before. Did you, Jake?”

“No, sir.”

Senator Rathborne strode to a table, opened a drawer, and took out a gleaming revolver. There was a hard light in his eyes as he came back. He fingered the gun, came close and jabbed it against “X’s” chest.

“Speak now,” he said, “or I’ll kill you. What did you murder my superintendent, Peters, for?”

The expression on “X’s” face did not change. His disguise was still that of Renfew, the spy. So perfect was his make-up that even at close range it was not detectable as such. His eyes burned with a steady flame as he returned Senator Rathborne’s gaze. The man was strong-willed, almost a fanatic. “X” knew his political reputation as he did those of all United States senators. He made it a point to follow such things. He had well-catalogued files, innumerable notes.

He was facing one of the hardest-headed lawmakers in the country. Rathborne was a man of great independence, a senator of the old school. But would he dare kill a man in cold blood, even a man he thought was a murderer? Agent “X” spoke then, his voice a soft drawl.

“I wouldn’t shoot if I were you, senator,” he said. “Circumstantial evidence isn’t always reliable. You’d have a lot of explaining to do if you killed me — and perhaps your own life may not bear investigating.”

It was a shot in the dark, bait thrown out, and Senator Rathborne rose to it. A trembling seized his body. His head came forward on his short neck like the head of a predatory bird.

“What do you mean?” he shouted. “What is there in my life that I can’t tell the whole world about?”

“You know better than I do, senator. But if you should kill two men—”

The Agent’s eyes were probing the senator’s, trying to read his thoughts. A mottled hue of fury came over Rathborne’s face. It did not seem to be the fury of a killer. It was the fury of outraged pride.

“The man is crazy,” he shouted.

He lowered his gun, stepped away, then strode swiftly across the room to a table. With trembling hands he picked up a phone, clattered the receiver on its hook. He put his white lips close to the mouthpiece, barked into it.

“Get me the police!” he said.

Chapter X

A THIN-LIPPED smile twitched the corners of Agent “X’s” mouth. Either Rathborne was the finest bluffer in the world — or else Peters had been wrong. “X” was inclined to believe the latter. There was no time to verify it now. He must get away before the police arrived. They might recognize him as Michael Renfew. If they did, it would put an end to his espionage work.

But the shotgun in the gardener’s hand was still pointed at his heart. A slight twitch of the man’s finger would literally blow him in two.

Rathborne, his face still mottled with fury, lighted a cigar. He had laid his gun on the edge of the telephone table. He advanced toward “X” again, blowing a cloud of smoke from his nostrils.

“We’ll see about your circumstantial evidence,” he said harshly. “They’ll send you to the chair or to an asylum where you can’t commit any more such atrocities.”

Agent “X,” face expressionless, slowly let his body sag. The movement was calculated, almost imperceptible. His arms were still raised above his head, but his knees were bent.

“Stand still,” said the man with the shotgun.

The Agent’s eyes had swivelled side-wise. He saw that a window in the room was half open. Suddenly he tautened his lax muscles, leaping to the left, toward the spot where Rathborne stood.

The gun in the gardener’s hand roared. The noise, in that confined space, was terrific. It seemed that a bomb had gone off. The charge of buckshot whistled past the place where “X” had been. It crashed into a glass-doored bookcase, shattered the glass, and riddled the books. Before the gardener could swing his gun, “X” had grabbed the senator.

Rathborne was a vigorous man, but Agent “X” was stronger. He literally whirled the senator off his feet, drew his body around as a shield.

When the gardener had once more got his gun into position, Agent “X” was behind the senator, holding the senator’s arms pinioned at his sides. If the gardener fired again, he would kill his employer.

The gardener’s face turned a sickly white. The gun in his hands wavered. Rathborne struggled fiercely and tried to kick back with his heels. The gardener shouted hoarsely.

“I can’t shoot — go and knock him out, Jake.”

The chauffeur sprang across the floor; but “X” pulled Rathborne back toward the window, dragging the senator’s heels over the floor as if he were a dummy. For a moment he held Rathborne with one arm only, reached behind with the other and raised the half-open window.

He suddenly released his clutch on Rathborne, shoved him straight forward toward the gardener with the gun, and stepped backwards out of the window.

He dropped on his hands and knees, moved close to the house, and darted along its sides. The head of the gardener appeared in the window just as “X” made the corner of the house. The shotgun roared again, but the bullets whistled harmlessly by “X’s” head. He was already around the building.

He had the whole night to hide in now. He sprinted for the dark woods that composed half of Rathborne’s estate. In an instant he was in their protective cover.

Stopping and looking back, he saw the gardener and the chauffeur come out with lanterns in their hands. They ran confusedly around the house, flashed their lights into the woods. They seemed to realize the hopelessness of trying to find the man who had escaped.

Tense and silent “X” waited. He had the idea of going back into the house and searching Rathborne’s safe after the police had come and gone.

A speeding automobile came up the long drive. Its headlights goggled weirdly through the wet shrubbery. It came to a stop before the front of Rathborne’s house. Four men leaped out. There was a hurried conversation on the front steps that “X” couldn’t hear. He could see the angry form of Rathborne still in his dressing gown and slippers.

THE police began scouting around the house. When they came dangerously near, Agent “X” stole back into the woods. He wasn’t afraid of being caught. He could see them in the lights from the house. They couldn’t see him.

They went back along the path that led to Peters’ cottage, and “X” followed. He wanted if possible to hear what the police said when they saw the torture victim. But the gardener with his shotgun was still alert. His face was white. He was more to be feared than the police. “X” couldn’t get close enough to hear.

Suddenly he stiffened and listened. Ten minutes had passed. Another car was coming into the drive, a second load of cops apparently.

“X” circled through the woods and peered from between the trees. Then suddenly his lips tightened grimly.

It was another police car, but the police were not alone. Three huge dogs leaped from the car ahead of the men. They had monstrous heads, powerful jaws, flapping ears. Bloodhounds.

This was something he hadn’t anticipated. Evidently Rathborne had put in another telephone call. The hounds were on chains. A beefy-faced man led them forward under the window from which “X” had leaped.

The great dogs sniffed the grass. Suddenly one of them lifted his head and gave tongue. The sound echoed through the still night woods. It was like a devil’s cry. The other two answered, strained at the leashes that held them. The beefy-faced man snapped them loose, and, with a bound of powerful legs, the three monstrous animals leaped forward toward the woods where “X” was watching.

With a sudden hissing intake of breath Agent “X” turned and fled toward the path along which he had come from the spot on the highway where he had left his car. The police and the gardener with his lantern and gun would follow the dogs. “X” was trapped if he didn’t outdistance them. He suspected that he would be shot on sight this time.

The dogs had gone to the spot where he had first crouched in the woods, watching. They bayed excitedly, then struck off, following his footsteps with the grimness of fate itself. He could hear them crashing and leaping in the wet woods behind him, hear the excited shouts of the men urging them on.

“X” flashed his tiny light, found the path. He sped along it, but the dogs, able to see in the dark, were plunging forward at twice his speed. Every second they drew nearer. They were outdistancing the men, leaving them far behind. They were overtaking Agent “X.”

The blood pounded in his veins. The old wound in his side ached. The baying tongues of the great hounds seemed to echo directly in his ears now. Their crashing grew louder and louder. He looked over his shoulder and saw the gleaming phosphorescence of their eyes. They had found the path, too. They were speeding along it, noses to the ground, great jaws slavering. “X” knew he would never make the car before the dogs reached him.

He stopped suddenly in the very center of the path. His lips moved in the darkness. From them issued a strange whistle, a note that was both melodious and eerie, a sound that seemed to fill the whole air at once. It was the whistle of Secret Agent “X”—unique in all the world.

It penetrated the deep woods, reverberated weirdly. It seemed to have a strange effect on the dogs. They stopped baying. They dashed up to Agent “X,” paused in a ring around him, their greenish phosphorescent eyes staring curiously. He spoke softly then.

“Nice fellows,” he said. “Quiet there! It’s all right.”

The leader of the great man-hunting beasts, trained to follow human scent, shuffled forward on padded feet. He thrust a wet muzzle against the Agent’s hand, licked his skin.

A bleak smile touched the Agent’s face. He had demonstrated again the strange power he had of inspiring friendliness in animals.

Another low-spoken word and the Agent turned and continued along the path. The men had found the path, too. They were shouting and running behind. But the dogs remained silent. As though the Agent had been their master they padded quietly at his heels, a strange and awe-inspiring escort.

He reached the highway with the police still three hundred feet behind. Moving swiftly he found his car still parked in the bushes. The hounds seemed loath to leave him. He patted their heads, snapped his fingers, and pointed back into the woods. Then he leaped into the car and backed out.

When the police broke through the highway the red tail-light of his roadster was nearly a half-mile distant.

But, though he had escaped the police, mystery and horror still hung heavy in the night. The sinister man in the green mask had beaten him to the secret that Peters held.

Hours later, that night, “X” went back to Rathborne’s house, entered, and searched the safe. But he found nothing to indicate that the stolen plans were there.

THE next morning newsboys were shouting in the street. The Secret Agent, still in the disguise of Renfew, bought a paper. Then his hands grew tense and his eyes blazed.

The story of Peters’ torture and death was spread across the front page. But that was not all. Senator Rathborne’s house had been robbed during the night. The safe and desk drawers in the senator’s library had been ransacked. A butler who had heard a noise and come in had been stricken with some strange form of paralysis. The paper said it was shock.

Both the murder of Peters and the robbery were attributed to the man who had escaped daringly through Rathborne’s window, using the senator as a shield. They were combing the city for a person referred to as the “Fiend Killer.” No mention was made of a man in a green mask. The police were looking for Secret Agent “X.”

“X” went back to Renfew’s office and paced the floor. Senator Rathborne had given an accurate description of him. There was danger if he appeared abroad in the disguise of Renfew, danger that he might be held and questioned. There was no doubt that Rathborne would identify him. It complicated matters. But he felt fairly secure in Renfew’s house.

He again took up his study of the code papers which Peters’ visit had put a stop to the night before. And again he was interrupted. This time by the jangle of a telephone somewhere in the house. Agent “X” had not known of its existence. He located it concealed inside a cupboard in an otherwise empty room on the second floor. He took the instrument out. It was evidently a private wire. His hands were tense as he put it to his ear.

A husky voice came out of the receiver: “This is Shank reporting. Anything for me to do today, boss?”

Agent “X” thought quickly. He understood now. A man in Renfew’s position would have some sort of secret organization, someone to help him collect the things he bought and sold.

“Yes,” “X” said. “I think so. Come over.”

“O.K.,” said the voice at the other end. “How about Zeb?”

“Where is he?”

“Right here.”

“Bring him along, too.”

The Agent hung up, eyes gleaming. In disguising himself as Renfew and coming to this establishment, he was acquiring a ready-made following. Shank and Zeb. There might be others, too. He wanted to see them. It was possible they would be of aid in finding out what he wanted to know. But it was ironic that he should be using Renfew’s men.

They came within twenty minutes, two shifty-eyed, dapper individuals. He watched closely to see whether his disguise would arouse their suspicion. But it didn’t.

Shank was hatchet-faced, flat-chested, with a stooping, furtive sort of gait. Zeb was smaller, stouter, an inoffensive-looking little man, except for the cold gleam in his eyes.

“X” wondered what dirty work they had helped Renfew in. Their clothes indicated he had been able to pay them respectable salaries.

Zeb grinned, took out a file, and commenced manicuring his nails. He turned them this way and that, inordinately proud, it seemed, of their glistening polish. Shank chewed gum steadily.

“Stick around, boys,” said “X.” “I’ve got irons in the fire.”

They went to a rear room of the house, drew a pack of dirty cards from a table drawer and began a listless game of pinochle. The Agent went back to his reports.

But the bell of the hidden telephone jangled again. This time when he answered it was a woman’s voice. There was a note of excitement in it.

“Hello, boss. There’s a gent wants to see you,” the woman said.

“Is that so?” The Agent spoke cautiously. He would have to watch his step. A slip, and one of these mongrel hangers-on of Renfew might grow suspicious.

“Yeah!” the woman said.

“Whereabouts is he?”

“Here in the restaurant. He was asking for you. I said I’d call you up.”

“What’s his name?”

“He won’t give it. He says you’ll know him.”

Agent “X” pondered tensely. He didn’t know where the restaurant was. If he asked the girl it would give his ignorance away, excite her suspicions. And “X” wanted to make sure who this man was who had called for him. It might be a police detective or a Government operative looking for Renfew. It might even be a trap.

“Tell him to go to Garfleld Park,” “X” said suddenly. “Tell him to take a bench in the west end. I’ll meet him there in twenty minutes. I’d like to look him over first, you understand?”

“Yes, boss.”

Risking police detection, Agent “X” slipped out of the house. The roadster he had hired was still parked down the block. He got in and drove to the east end of Garfield Park, where he stopped again.

His movements became as cautious as a stalking cat. He lighted a cigarette, turned his collar up and his hat brim down and shuffled slowly along imitating a weary down-and-outer. His eyes were piercingly alert.

Then, as he approached the west end of the park, his pulses quickened like suddenly released triphammers. There was a figure on one of the benches — a well-dressed man, wearing spats and carrying a stick. He was big, blond, and he had coldly penetrating blue eyes. Agent “X” recognized him at once.

The man was Otto von Helvig, embassy attaché and ex-Prussian spy.

Chapter XI

FOR the moment Agent “X” continued his role of down-and-outer. Half of his face was hidden by the collar of his coat. He moved toward von Helvig at the same slow shuffle. When he came opposite the attaché he spoke in a husky croak.

“A few pennies for a cup of coffee, mister?”

Agent “X” thrust out one hand, shaking it as though he were afflicted with palsy.

Von Helvig cursed under his breath and waved him away. But “X” stood his ground, staring at the attaché fixedly. The Prussian lifted his head angrily, glaring at the man he took for a panhandler. Then his expression changed. He leaned forward, smiled suddenly, showing gleaming white teeth.

“You old fox, Renfew! You fooled me — even though I was expecting you.”

“Herr von Helvig,” said the Agent respectfully. “This is a great pleasure!”

The attaché eyed “X” sharply.

“You’ve changed very little since I saw you two years ago, Renfew! And you’re still up to your old tricks.”

Agent “X” bowed. “A man must make a living, Herr von Helvig.”

Von Helvlg touched “X’s” arm. “I am due at the legation now,” he said. “My time is brief. But there’s something I want to ask you, Renfew. You are a man who keeps his ear to the ground. You are a fox who listens at the rabbit holes. You don’t miss much. Have you heard recently of any great theft from the United States Government?”

It was a surprising question coming from von Helvig. “X” knew that the man’s clean-featured blondness and the babylike candor in his blue eyes hid a cunning, crooked brain. He hedged.

“Perhaps,” he said. “Why do you ask?”

“Just a matter of curiosity,” said von Helvig evasively. He opened his wallet, took out two century notes, folded them, and held out his hand.

“Here is the price of your cup of coffee, Renfew. Now come on — loosen up and tell a fellow what you know.”

“X,” playing the role of Renfew, waved the money away.

“I have changed, my dear von Helvig, since we last met. My business, if I may say so, has grown. I no longer accept — ah — small gratuities.”

Anger reddened von Helvig’s blond face. He hastily pocketed the money.

“My mistake,” he said. “I’ll be frank with you. A lovely woman has come to me with a certain proposition. She claims to know where something of singular importance, stolen from the Government, may be recovered. She has asked my cooperation in securing it. Do you know to what she is alluding, Renfew?”

There was an odd, avaricious glitter in von Helvig’s eyes. “X” was puzzled. Was von Helvig really seeking information; or was he trying to lay a trap? “X” must watch his step, impress von Helvig with his knowledge. He bowed very low and spoke softly.

“If the lady in question is very lovely, she has done well to ask the cooperation of the gallant — Karl Hummel.”

It was as though “X” had struck von Helvig a blow. Every muscle in the man’s body tensed. His eyes narrowed to points of steel. His hand moved across his face where a miracle of plastic surgery had been performed. Only the tiny scars in his cheek were reminders of it.

“You are crazy, Renfew,” he said harshly. “What do you mean by calling me that name — Hummel?”

“Nothing,” said the Agent blandly. “Just a whimsy of mine. Perhaps it was a mistake.”

For a moment von Helvig sat in tense silence, his eyes probing those of the Agent’s. Then he took out his wallet again, adding three more century notes to the two he had offered the Agent before, and held them out.

“I must insist that you take this small token of my good faith,” he said. “I am going to take you completely into my confidence, Renfew. I want you to meet the lady in question tonight. I want you to hear her story — and be my adviser. You are a man of even more remarkable talents than I had estimated, but—“ Von Helvig suddenly leaned forward and laid steely fingers on the Agent’s arm. His blond face became a mask of cruelty. His eyes were pin points of murderous light. “If you value your life, Herr Renfew, you will keep faith with me. I am no man to trifle with.”

“Nor I,” said the Agent. “I think we understand each other.”

“This evening then,” said von Helvig. “We shall have dinner together — you and I and the lady I spoke of. Be in this same spot at six-thirty. I will drive by and pick you up.”

“Very good, Herr von Helvig.”

Conscious that the man’s eyes were still boring into him, Agent “X” turned and shuffled off. His pulses were racing. The lead that the murdered Peters had brought him had apparently been false. This one promised results. Unless von Helvig was setting a trap for him, he might learn, within the next twelve hours, the location of the stolen plans.

BACK in Renfew’s house, Agent “X” gave instructions to Shank and Zeb.

“I’ve got a job for you,” he said. “Go to the German embassy. Wait outside and watch for the attaché, Otto von Helvig. He is tall, blond, blue-eyed. There is a slight scar on each cheek. If he leaves the building at any time during the day, follow him. Check up on every movement he makes — and report back here at six this evening.”

The two men rose from their listless card game.

“We got you, boss,” they said.

When they had gone “X” paced the floor a moment. His nerves tingled for action. He seemed to be getting closer to what he sought. His disguise as Renfew had been a wise move. It had brought him in contact with von Helvig. Was it possible that the lovely lady he mentioned was—

“X” smiled grimly to himself. Then he looked at his watch. Ten o’clock. At twelve the plane he had asked Betty to come in would land at Washington Airport. He’d had no answer to his telegram. He’d expected none. But he wanted to make sure of her arrival. He could not meet her openly; could not, at this time, run the risk of being seen with her, but he could see whether she was on the plane.

At a little before twelve, his disguise changed to that of a sallow-faced young man, Agent “X” crossed the Potomac on the Highway Bridge and turned into Military Road. Arlington was beyond. The Hoover Airport was at his left. The Washington at his right. The deep-throated hum of airplane motors filled the sky. Out-of-town tourists were going up from Hoover Airport on short sight-seeing hops over Washington.

The sky had cleared. The sun was shining. But to “X,” who knew the strange events of the past twenty-four hours, a sinister menace hung over the city. It wasn’t dispelled by the bright sky nor the sunshine.

He found where the tri-motored E.A.T. plane bearing Betty Dale was to land. He waited at the edge of the field, saw the huge ship appear, a great dark bird on the horizon. He saw it come down to a stately landing, taxi up to the field office.

An attendant unrolled a carpet. Steps were set in front of the big plane’s metal door. A laughing group waited for the arrival of friends and loved ones.

In this group Agent “X” saw Suzanne Blackwell. It meant that Betty had sent her a wire. It meant that Suzanne was here to meet the Agent’s blonde ally.

His pulses quickened as the plane’s door opened and the passengers piled out. The loveliest of them all was the trim-figured little blonde who stepped to the turf of the field and ran toward the spot where Suzanne Blackwell was waiting. Hair the color of imprisoned sunlight peeped from under her blue cloche hat. Her fresh young lips were softly red. Her blue eyes were dancing. This flying trip to Washington was a lark to Betty Dale.

Fondly the Agent watched as Betty and Suzanne embraced. For a fleeting second he saw Betty’s eyes rove over the crowd, lingering on each face. He knew she was looking for him, knew also that his disguise had fooled her. He would not make himself known till the time prearranged for their meeting. The time when furtive, crafty eyes which might be watching would be least suspecting.

With her arm linked in Suzanne Blackwell’s, Betty walked toward Suzanne’s waiting roadster. “X” wouldn’t see Betty again until night fell. But he knew now that she was in Washington. He knew that she was ready to help him.

He frowned a moment, a shadow in his eyes. Her fresh, blonde beauty seemed a contrast to the dark forces now in motion. A strange sense of uneasiness filled him, a foreboding, as though some secret voice were warning him. He regretted at that instant that he had asked Betty to come.

Then he remembered that he was Secret Agent “X,” pledged to aid his country. He must put all fear aside, even fear for others, as he had fear for himself. He turned and strode back to his own waiting car.

At six that evening, disguised again as Renfew, he received the report of Shank and Zeb.

“We spotted von Helvig, boss,” Shank said. “We didn’t lose him all day. He had lunch with two guys, one from the Mexican embassy, another who was a newspaper gent. He left the embassy on Massachusetts Avenue, and stopped for a half-hour in a joint on Thirteenth Street. There he talked to a guy in a back room. It was screwy, boss! This guy looked like von Helvig’s twin. He left by the back way and von Helvig went to the Wilmott Hotel. He’s there now!”

“Good work,” said Agent “X” softly. “Thanks.”

AT shortly after six that evening a closed car slid to a stop at the curb near Garfield Park. A tall man was driving. He was dressed in the height of style, a soft gray hat on his head, spats on his ankles, yellow pigskins on his hands.

He was a man who bore a marked resemblance to Otto von Helvig of the German embassy. But there was a hardness about him, a wolfishness, that the more polished von Helvig managed most of the time to conceal. This man was definitely a member of the underworld.

There were three others with him, harsh-faced, flat-chested young men, overly dressed. As the car stopped, the driver asked a question.

“Everything ready, boys?”

The three men with him were busy for a moment. They took wicked-looking automatics from their pockets. Over the ugly snouts of these they slipped awkward cylinders that made the guns seem grotesquely long — silencers.

“All O.K., Al,” one of them said.

“You can handle ’em all right that way?”

“Say — you oughta know us.” There was a note of evil pride in the voice of the man who spoke. “We’ve knocked off bigger mugs than this.”

“O.K. But any slip — and there won’t be a pay-off. The big shot behind this is a hard bird to please. Wait till I give the signal — then do your stuff!”

The blond and dapper man who looked like von Helvig showed his teeth for a moment in a wicked smile. He motioned with his hand for the others to get out.

They left the car and vanished into the shadows along the square like slinking gray wolves.

The man in the car glanced at the clock on the dashboard. It was now a quarter past six. He took a cigarette from his pocket, lighted it. Inhaling luxuriously, he, too, got out of the car and sauntered toward the west end of the park.

Now more than ever he looked like the Prussian attaché. Anyone seeing him from a distance would be fooled. When he arrived at the park’s west end, his sharp eyes swiveled. He seemed to be counting the benches.

He turned, walked up to one and sat down — the very bench that von Helvig had occupied that morning. He crossed his legs, blew smoke from his nostrils, leaned back comfortably. The three men he had brought with him crept noiselessly closer, the silenced automatics in their hands. They were awaiting his signal. The stage was set for murder.

A bell across the park struck a single booming note. Six-thirty.

Even as the stroke died away on the night air, a man’s shuffling figure appeared. He came from the direction of the park’s east end. Hat brim turned down, collar turned up, the man had the wrinkled features of Michael Renfew, dealer in espionage. The man was Secret Agent “X.”

FIVE hundred feet away, he saw the figure on the bench. Piercingly bright eyes stabbed out from under the Agent’s hat brim. The figure ahead looked like von Helvig. The German attaché had apparently kept the appointment. Tonight, it seemed, “X” was going to meet the “lovely lady” who knew where the Browning plans could be discovered.

Simulating a down-and-outer, “X” continued to shuffle forward. The man ahead, smoking on the bench, did not turn his head. He seemed to be deep in meditation.

The Agent was within a hundred feet of him now. Fifty feet — twenty-five. The Agent moved toward the bench — and not until then was the suspicion he had had confirmed. The man on the bench wasn’t Otto von Helvig. The man was a perfect stranger to “X.”

“A penny for a cup of coffee, mister?”

The Agent’s voice was the cracked, querulous voice of an old panhandler. His skinny fingers trembled. The stranger on the bench lifted cold eyes and shook his head.

“Not tonight,” he said. “Beat it.”

The panhandler dropped his skinny hand, turned and shuffled on. The man on the bench followed him with eyes that were suddenly bright. His lips skinned back in a mirthless grin.

Abruptly he took a white handkerchief from his coat pocket, opened it and blew his nose loudly. As he tucked the handkerchief back into his coat, three figures moved out of the shadows that made blotches on the park’s grass plot.

Their dark clothes blended with the shadows; their feet were noiseless. Swiftly, murderously, they crept upon the man disguised as Michael Renfew.

It was at the juncture of another asphalt path that they came close enough to fire. Simultaneously then they raised their guns.

At the last minute, as though some secret sense had warned him, the shuffling figure turned. But he appeared to be too late. The three hired killers fired.

There were no smashing explosions in the night. Only faint flickers of flame and three muffled reports. Then the sharp spat of lead striking where the guns were aimed.

Agent “X” lurched backwards as though the force of the lead had pushed him off his feet. One gurgling cry came from his lips. His knees bent under him. He sank to the asphalt, twitched a moment, and lay still. The gunmen pocketed their weapons and slunk away. The man on the bench, humming softly to himself, rose and sauntered in the opposite direction.

Chapter XII

FOR nearly five minutes, or until the slow measured steps of a patrolling cop sounded, Agent “X” lay just as he had fallen. Then, magically it seemed, he rose to his feet, moving quickly into the shadows. His eyes were gleaming like living coals. His lips were harsh. There was the trembling pulse of excitement in his body.

In the semigloom beside the path he reached up with tense fingers, feeling the front of his coat. There were three holes in the cloth. He probed in one; probed down to the hard resilient material of the bullet-proof vest he wore.

Half expecting trickery, Agent “X” had come prepared. The vest, cleverly molded to his torso, covered the whole of it. It had witnessed the shock of bullets many times before. He had established one thing tonight. Otto von Helvig didn’t stop at murder.

But the Agent wasn’t sure he had played his own hand wisely. In this desperate game, with so many crosscurrents, no man could proceed in a straight course. The Agent was a gambler. A high adventurer in an underworld of terror. A man who took chances with death itself in an effort to balance the scales of justice.

He sped across the park silently, swiftly. In the darkest shadows, amid a clump of shrubbery, his fingers roved over his face. His movements in the next hour called for a new disguise. Michael Renfew, supposedly dead, must stay dead.

It was a relief to get the rubber cap, imitating baldness, off his head. It was a relief, too, to peel the transparent tissues, creating a network of wrinkles, away from his skin. He took a few other materials from the lining of his coat. He used them with the skill of a man who was master of a thousand faces.

When he emerged from the shadows, he was young again, utterly unlike the man who had gone down under a volley of murderers’ bullets.

He got in his car and drove swiftly through the night to the Wilmott Hotel, the hostelry where von Helvig was stopping. He was not an instant too soon.

Otto von Helvig, tall, immaculately dressed, suave as only a diplomat can be, was just leaving his key at the desk. No one looking at his bland blond face would have guessed that here was a man who, less than an hour before, had engaged assassins to kill a fellow human being. But “X,” posing as Renfew, had dared to bring up a ghost from von Helvig’s past — dared to call him Karl Hummel. That in itself, “X” guessed, had been reason enough for the attempted murder. Perhaps there was a still more sinister motive.

He watched von Helvig go to the street, saw the doorman signal a taxi. The taxi sped along Pennsylvania Avenue. The Agent followed in his own hired car. Again his pulses throbbed with excitement. He believed he knew where von Helvig was going — to keep a tryst with a beautiful lady. Was it possible he knew the lady’s name?

Von Helvig’s taxi drew up before a building of fashionable apartments. He paid the driver, walked nonchalantly into the elaborate foyer.

Agent “X” drove on, parking a full block away. He walked briskly back. Von Helvig had disappeared. In the bronze directory Agent “X” looked for a name — and found it. Lili Damora! This, he believed, was the lovely lady von Helvig had come to see.

The eyes of Agent “X” were snapping. Lili Damora’s apartment was 4E. He must learn what was said at this meeting between von Helvig and the sinuous-bodied woman from Budapest. To do so he was prepared to gamble with fate again.

He walked boldly past the uniformed doorman. The girl at the telephone desk stopped him.

“Miss Damora is expecting me,” “X” said. Experience had taught him that a confident manner allays suspicions. He went directly to the elevator, ascending to the fourth floor.

Here he became more cautious. The corridor was empty. Faint sounds of radios and conversation came from behind the closed doors.

Agent “X” walked forward to 4E. His eyes darted alertly about This was evidently a large apartment. There were two doors. One marked with the letter and number. The other blank. That would be a bedroom. The first probably opened on an entrance hall with the living room off it. To go in there would be inviting disaster.

He stopped by the first door, listened. The faint sound of voices reached his ears. He moved on to the second, and could hear nothing.

The Agent worked quickly then. Keeping a sharp eye out along the corridor, he used his compact tool set with its implements that would open any lock. In a few seconds, with hardly a sound, the door moved inward, and he found himself as he had expected, in a bedroom. Von Helvig’s coat, hat, and stick were on the bed. Voices came from a room beyond — the living room.

THE Agent’s nerves were tingling. He crept forward across the dark floor. Perfume bottles and powder jars stood on the dresser. There was the vague odor of scent in the air. This was the exotic Lili’s chamber. A strange place for Agent “X” to be.

He put his ear to the door, listened intently. He hoped he would hear enough in the next few minutes to size up the situation. The throaty voice of the brunette reached him. His eyes shone.

“Don’t be impatient, Otto. I am hungry. Let us have dinner first. We can discuss this afterwards.”

Von Helvig’s answer was harsh.

“It is safer here — where there are none to listen. You know as well as I that every restaurant in Washington is a hotbed of espionage. Tell me what you have to say. Then we can enjoy ourselves at dinner — and at the ball afterwards.”

“Yes — the ball,” said Lili, speaking in a husky drawl.

“Come — come, Lili, don’t fence, or I shall think you are stringing me along, as the Americans say.”

“Perhaps I am,” said Lili softly. “Perhaps I pretend to know things I do not know just to enjoy your company, Otto.”

Von Helvig gave an angry exclamation.

“Don’t,” said Lili. “You look so fierce that I am afraid. I shall be frank with you. I must have two or three days more.”

“You don’t know where they are then?”

“Not precisely — I told you that. But I think I know how to go about finding them. Two or three days more, Otto, with your help, and we shall have them.”

“They are here in Washington then? They haven’t been taken away?”

“If it were otherwise how could I expect to get them,” said Lili evasively.

“I hope you realize, Lili, that I’m not a man to be trifled with?”

The Agent’s mind leaped back. That was what von Helvig had said earlier in the day to him — and the man had proved it. If Lili was fencing, she had better watch out.

What “X” had heard was not encouraging. Lili herself did not seem sure. Perhaps she was only playing a game with von Helvig. Or perhaps she really knew. In that case it would mean hours, perhaps days of patient shadowing. Could either Shank or Zeb be trusted? Wouldn’t Betty Dale be more of a help? Lili Damora moved in the diplomatic set. He would ask Betty to discover if possible exactly who her friends were and how she spent her days. He listened a moment more.

“I am disappointed,” von Helvig was saying. “Very disappointed.”

“Don’t be sulky, Otto. Trust me — and remember — keep your eyes open tonight. Every one of importance in Washington will be present at the ball, including Senator Cobb!”

The Agent started. Was Lili merely trying to confuse von Helvig. It almost seemed so.

“X” moved back across the bedroom to the door. Von Helvig would be coming for his coat presently — and “X” had heard enough to convince him that a fog of mystery still hung over the stolen Browning plans. It was still a race between himself and the green-masked murderer who had killed Saunders and Peters.

AMONG the brilliant guests at the home of Senator Marvin Foulette that night was a young man introduced as Raphael Sancho, descendant of a wealthy South American family and the nephew of a president.

He was here in Washington, it was said, to study the American form of government at close range. He was an ambassador of good will. It was at the request of a high government official that the Foulettes had invited him at the last moment.

They welcomed him at the door. Mrs. Foulette, a dignified, white-haired lady, murmured a conventional phrase of greeting. The senator shook his hand perfunctorily. He passed on into the ballroom of the senator’s big home, now ablaze with lights, and filled with people. A few débutantes cast admiring glances at him, but otherwise he was unnoticed. There was no representative present from the particular country from which he came.

The young man, however, appeared perfectly at ease. He strolled about the big room and, using excellent Spanish, engaged the Brazilian ambassador in a conversation concerning South American tariffs.

As his tongue rattled off dry statistics, his alert eyes scanned the main door. The even flow of his words ceased for a moment as Senator Blackwell and his party arrived. Suzanne Blackwell was with her father, escorted by Sam Barkley. Suzanne’s college chum, Betty Dale, held the arm of the senator.

It was upon her that the eyes of Raphael Sancho dwelt. And in their veiled depths was a look of fondness and admiration.

The girl whose hair held the golden glint of imprisoned sunlight was radiantly beautiful tonight. A simple green dress set off her dainty figure. Her eyes held a sparkle of excitement, making them seem as bright as the single jewel at her throat.

Others arrived, Lili Damora, dark, almost serpentine in her lithe grace, with full, pouting lips and a dazzling smile; Otto von Helvig, wearing the ribbon of a military order across his chest, courtly as a prince of the blood.

Upon these, too, the eyes of Raphael Sancho rested for a moment, while a thin smile twitched the corners of his mouth. Senator and Mrs. Foulette left their position by the entranceway and circulated among the guests. They took pains to introduce Raphael Sancho to a number of eager young women. It wasn’t long before he was gliding around the ballroom to the strains of a languorous dance from the Argentine.

But his eyes still followed the form of the girl in the green dress, the girl with golden hair and a single jewel at her throat.

Betty Dale seemed at times preoccupied, too. Once her eyes met Sancho’s and looked beyond him. Again he smiled thinly. Not until a series of formal introductions led him to the side of Suzanne Blackwell did he mention what was on his mind.

They had danced to one number. He was leading Suzanne back toward her father. He spoke softly.

“The girl in the green dress, with the golden hair. Is she not a friend of yours, Miss Blackwell? Did she not enter with your party?”

Suzanne Blackwell laughed. “Yes,” she said, “and I am jealous, Señor Sancho. I believe you danced with me just to get an introduction to her. My friend Betty Dale is always pulling the choicest plums out of the pie.”

“Plums?” said Sancho vaguely. “Pie?”

“That’s right,” said Suzanne. “A nice kind of fruit, you know, and an American form of pastry. But come — here’s Betty now. I’m sure you’ll find her a more accomplished dancer than I.”

The young Señor Raphael Sancho bowed low over Betty Dale’s slim hand.

“Miss Dale,” he said. “I am so happy to meet. Is it that you will dance with me?”

Betty’s voice was perfunctory as she accepted. Her expression was slightly worried. Someone she had hoped to see was not here. Raphael Sancho whirled her into the rhythm of a sinuous bolero. His tones were ingratiating as he talked with his charming Spanish accent. But she hardly listened. To her he was just another of the indolent young men to be found in the gay society of America’s capital. Betty Dale, for all her youthful appearance, had the keenness of maturity and experience.

It wasn’t until Raphael Sancho uttered a sudden mysterious phrase in perfect English that Betty became electrified.

“There are shadows beneath the sunlight,” Sancho said.

The blue eyes of Betty Dale grew bright. She tensed in the arms of Raphael Sancho. Her gaze met his.

“Careful,” he added. “Wolves lurk in the shadows.” Then, as the music stopped, he drew her to a seat in the corner. “Let me show you a picture of my country, Miss Dale.”

HE drew from his pocket a small photograph of a South American capital. Betty Dale stared with wonder. Suddenly the man called Raphael Sancho flipped the photograph over, holding it in his palm so that only Betty could see. In that moment she held her breath in excitement. A single letter showed on the back of the picture, written in some strange ink. It was the letter “X,” and under the glare of the lights it slowly began to fade.

“You!” she said. “I did not guess!” Then, in spite of her effort at self-control, the color in her cheeks deepened. Her eyes became ever more bright. The man whom she most respected and admired in all the world was at her side. The man whose real face she had never seen, but whose strange, dynamic personality had cast a spell over her emotions so that all other men by comparison seemed lame. The man, whom, deep in her heart, she loved.

But Betty Dale knew that “X” had only his work to think of. She knew that the time might never come when they could be more to each other than they were now — loyal, trusting friends and allies. She knew that she had no right ever to interfere with his strange, caring career.

The Agent pocketed his photograph. He looked quickly around.

“There is a small alcove at the end of the room,” he said. “Perhaps we can continue our discussion of South America there.”

They circled the dance floor, a youthful, graceful couple. Eyes followed Betty Dale enviously because she had apparently captured the interest of the dashing Raphael Sancho. Other eyes looked with envy upon Sancho because he was holding the attention of the room’s loveliest girl.

They sat on a bench in the alcove and Betty Dale spoke quickly.

“I have found out nothing except that both the senator and Suzanne seem upset. Ferris has gone to the sanatorium again. But I don’t thick that’s what’s worrying them. It is something else.”

“Yes,” said the Agent. “Be careful, Betty. Be on your guard even when you are talking to Suzanne. She has friends. It is these friends I want you to watch. Find out all you can about Lili Damora, and the German attaché, Otto von Helvig. Find out also about Senators Foulette, Cobb, and Rathborne: Remember anything you hear.”

“I will,” said Betty. “Is it something very important?”

“Very,” said the Agent.

“And dangerous?”

A shadow came into the Secret Agent’s eyes for a moment. He was thinking of Green Mask.

“I have said be careful, Betty. Be on your guard every instant.”

Betty touched his arm suddenly. “Nothing will happen to me. It is you I am thinking of. I read about the terrible murder of Senator Rathborne’s man. Had that anything to do with what is worrying you?”

The Agent nodded. “Yes, Betty, it had. But my reason for being in Washington is more vital even than the hunt for a murderer. It is something which concerns the safety of America. It was that which made me ask you to come.”

Betty started to answer, then suddenly stopped. She stared across the ballroom, eyes wide with amazement. Something strange was happening. It was a warmish spring night. Windows on both sides of the ballroom were open. Now a smoky haze was coming through these windows. People were moving back.

A man’s voice was raised in sudden excitement.

“Fire!” he said.

The soft throb of the orchestra came to a stop. Low conversation was hushed. Agent “X” rose to his feet, stepped forward. He moved quickly toward one of the open windows which gave on a wide lawn outside. Then he paused and sniffed, nostrils dilating.

A strange odor was in the air. The haze of smoke was curling in ghostly streamers through the whole big room. This was not fire — it was something else. A girl near “X” gave a cry and swayed against her escort.

“I’m fainting,” she gasped. “Air — please.”

But she did not reach the door. She had taken only two steps when her knees gave way and she collapsed on the polished floor. Others were staggering, too. The smoke in the air made a dim veil, blurring faces. Or was it the effect of the strange scent? Agent “X” did not know. This time he leaped toward the window.

But his leap ended in a drunken sort of stagger. For a fresh breath of the strange smoke had entered his nostrils. It made his senses swim. He heard other cries around him; saw, as through an awful fog, that men and women in all parts of the room were sinking to their knees, collapsing on the floor.

He turned back toward Betty Dale, tried to reach her. She, too, was collapsing, slumping sidewise in the seat, her head falling forward on a wilting neck.

Chill horror grasped Secret Agent “X.” In a frenzy of effort he tried to go to her, get her out of this room. But his muscles would not respond. Like a man caught in the grip of a horrible nightmare that paralyzes while a danger he cannot avoid creeps upon him, Agent “X” fell to the floor. There he lay, immobile, unable to move — slipping closer and closer to the borderland of unconsciousness.

Chapter XIII

AGENT “X” struggled fiercely, his iron will urging him on. He would not give up as other men did. Physically helpless, he fought to retain that spark of consciousness which still made him able to see and hear. Turning his head he breathed through his cupped hands, holding them across his face, drawing the air through tense fingers to purify it.

Numb in every muscle, his eyes could still focus. And he was amazed at what he saw.

Hideously evil faces appeared in the windows as the strange haze began to clear. Sinister brown-skinned figures glided into the room. There were at least a half-dozen of them, and they began robbing the inert guests with calculated thoroughness.

They stripped rings from fingers, links from men’s cuffs, necklaces from the white throats of women, tiaras from their hair. Jewels were all they seemed to seek. Everything that glittered they fell upon and pocketed as a flock of hungry vultures might pluck flesh from bones.

“X” could not stop them. He could not even cry out. The single small jewel that Betty Dale was fond of, an heirloom from her dead mother, was taken from her throat as he looked. Then fresh horror came.

Two of the men were lifting Betty Dale up. He saw as in an unbelievable nightmare her body rise from the floor, saw her blonde head hang limply, saw her borne toward the door.

Icy hands clutched at the Agent’s heart then. Frantic blood surged in his veins. He tried to move, but still the drug held him. An invisible net seemed spread over his whole body.

His lips moved to form words: “Betty Dale! Betty Dale!” But they made no sound. He alone of all the guests was witness to her abduction. And he was unable to prevent it. It was plain to him who these brown-skinned men were. This was the poisonous Malay horde whose master was the green-masked killer. These were the men who had tried to murder him with the dart on the lawn of Blackwell’s house, the same who had tortured poor Saunders to death with the hideous Kep-shak. And now they were taking Betty Dale away.

More terrible than torture of the body was the mental torture that gripped Agent “X.” Except for him, Betty Dale would be safe in her own home city hundreds of miles away. If he had not called her, this would not have happened.

As he lay, fighting for the power to move, bathed in cold sweat, a shadow fell on the floor beside him. He could not turn, but his eyes rolled feebly. The shadow belonged to one of the brown-skinned men.

The man stooped, pinned a note to Agent “X’s” coat. Then he moved after the others, and the Agent caught a last glimpse of Betty Dale’s golden head. A last glimpse of her pale, lovely face.

There came times when the Agent’s dauntless spirit seemed to master his flesh. This was one of them. Overcome like the others by the strange smoke that had filled the room, Agent “X” refused to let it conquer the fighting heart within him.

The fingers of his right hand began to move. A quivering set their tips in motion. They curled up slowly until his fist was clenched. Then his arm moved also, beginning at the elbow, drawing toward his chest. The fingers plucked the note that the brown man had left. His eyes scanned the words that the note held. And the words seemed to burn into his senses like fire, eating away the coma that held him.

“You cannot win, Agent ‘X,’” the note said. “You saw Saunders die, and were horrified. You were horrified, too, when I killed Rathborne’s man, Peters. But you have not seen all. It is terrible to die, but a living death is worse. There are poisons that act quickly. There are others that gnaw at the nerves themselves — destroying what can never be repaired. And my slaves are masters of their art. I have your friend Betty Dale, who came to Washington to aid you. Through her I issue a command. Make no further investigation into this case. Leave the city at once — or my slaves will practise their art on her. She will be stricken, paralyzed for life, her mind and body shattered forever. Take warning and obey. The Green Mask.”

A groan came from the Agent’s lips. Horror pressed upon him. But the note was the last thing needed to drive him to a frenzy. He had seen the green-masked man’s tactics. He knew that even if he did drop the case and leave, Betty Dale would not be safe.

His other hand was moving now. His legs were beginning to obey. He was fighting the battle of his life. Even before he could stand, he crawled toward the door through which Betty had been taken. It opened on a tiled porch with the lawn beyond.

HE reached the door, thrust his head into the darkness. The chill of the night air helped him. He felt new life coming into his veins. Clutching the side of the door, he drew himself to his feet, stumbled out onto the lawn. Once he fell on his face, striking his head on the ground, but he was up in an instant.

Through shrubbery he saw a glint of water and then he understood. Beyond the lawn was the river, and it was toward this that the dark-skinned men had gone. It was from the river that they had come.

He crept forward toward the spot where the senator had a boat wharf, and he saw skulking figures ahead. There was a dark shadow at the right of the wharf. The figures merged suddenly with this. Then came the sound of a muffled engine. The dark shadow moved out.

It was a boat, long and low to the water. It backed away from the wharf, turning in a half-circle. White foam, appeared under its bow. A white wake showed behind it. And the sight of it moving away spurred Agent “X” to fresh action.

At the left of the wharf was another shadow. Senator Foulette himself was a yachtsman. “X” leaped along the wharf, eyes stabbing the darkness. Water lapped against a polished hull. A runabout was moored to the wharf, securely fastened with ropes.

The Agent drew a knife from his pocket. No time to untie lines now. He slashed, freed the moored craft, and jumped down into it.

Familiar with all types of engines, he slid into the padded seat up front. Then a harsh exclamation came from his lips. A locked ignition switch met his groping fingers and each second of time was precious. Face set, eyes burning, he fumbled under the seat, drawing out an engine wrench. He leaned forward over the rounded wind glass and smashed at the plywood deck. He struck at it like a man in a frenzy till the thin boards gave way. Then he tore at the wood with his bare hands and reached inside.

Under the decking, in front of the instrument board, he found what he sought — the wiring of the ignition. He pulled two flexible cables out, joined their ends together and completed the circuit. As he did so his eyes strained off across the water. He could still hear the engine of the boat ahead.

Then he pressed the starter, heard its muffled whine. He moved the spark forward, drew the throttle back, and his own engine broke into life. Afraid that its starting roar might be heard, he let it idle for a moment, backing slowly from the wharf.

He eased the runabout’s nose around toward the white wake that the other boat had left. His eyes burned with a hot, tense light. His fingers pushed the throttle forward, and the boat he was in moved ahead.

He followed the white wake that showed on the water. His eyes sought each bit of foam, each breaking bubble. He could no longer see the other boat. It had no lights. But he was following it, following Betty Dale. He swept on to where the river widened and the shores became less populated. On by salt marshes and tiny islands.

IT was toward one of these, grass-grown and covered with dense shrubbery, that the wake of the boat ahead led. “X” cut his speed and crept along. A minute after he had done so he heard the engine roar of the other boat diminish in volume.

He kept out of its wake now, afraid that his own craft would be seen as a black shadow in the foam. With his engine barely turning over, he nosed in near enough to see the other boat thrust between shrubbery that grew close to the water’s edge.

Five hundred feet distant he circled the island. Caution was all that would save Betty now. Beyond the island the mainland showed. A channel separated the two. The Agent crossed this and brought his boat among the trees. To one of them he tied it, and slipped out of his coat and shoes.

If there were eyes watching, he dared not take the boat to the island. It would be too great a risk — for Betty Dale. Instead he dropped over-side, silently as an otter. In long swift strokes he swam ahead, slowing when at last the thick vegetation of the island loomed up.

Then his feet touched; he moved up to a narrow sandy shore. Bushes higher than his head grew here. He skirted them, moving along the beach until they thinned.

His eyes were growing used to the faint light of the stars. He could see more plainly now, and as he pushed forward toward the island’s center the dark bulk of a building rose. It seemed a huge old barn.

Then Agent “X” stopped dead in his tracks. A shadow rose before him. Green Mask was behind all this and Green Mask did not do things by halves.

A Malay word was grunted at him. He answered in the same language; but what he said did not seem to be the right thing, for the shadow moved toward him inquiringly and “X” backed away.

His muscles were tense as coiled springs. He knew that death was close at hand. But for Betty Dale’s sake he must not die. Deliberately he drew the man away from the building. If there were other guards “X” did not want them to hear.

The Malay spoke again. “X” was almost at the water. He crouched behind a bush, waited, and the brown-skinned man came up slowly. Then abruptly, as though his eyes could penetrate the dark, the Malay turned and leaped. As he did so, he pulled something from his belt. A curved knife glittered wickedly in his hand.

Chapter XIV

THE man’s attack was like the death lunge of a hooded cobra. He struck for the Agent’s heart, seeking to bury the knife blade to its hilt; struck with the quick ferocity of some jungle creature to whom killing is a natural act.

The Agent’s sidewise lurch was all that saved him. He saw the knife flash by, clutched the wrist that held it, and with his free hand gripped the Malay’s face, pressing his palm across the brown-skinned killer’s mouth. There must be no outcry. Any disturbance would cause a murderous horde to descend upon him.

But the Malay was a cyclone of destructive fury. He twisted like a snake, tried to bury his teeth in the Agent’s hand, tried to wrench his own fingers loose and slide the knife along “X’s” straining neck.

The Secret Agent’s fingers clamped like steel over the man’s jaw. They dug into his cheek, bent his head forward. But bushes cracked and rustled beneath their moving bodies. This sound, too, would bring disaster.

“X” drew the Malay toward the water then, down the small, sloping beach into the chill river. The man tried once to cry out. But only a hissing grunt came. The Agent let his body sink, pulling the man in after him. He kicked his legs in powerful scissors strokes, pushing violently away from shore.

The current caught them. They began to drift downstream. But the Malay was like a squirming, thrashing fish. He reared up, bringing his full weight down on “X,” forcing his head under. They sank below the surface together, fighting furiously.

With a sudden vicious thrust, the Malay caught “X” in the stomach with a knee. Racking pain shot through the Agent’s body. For an instant his grip weakened, and in that instant the Malay broke away.

In the black water “X” felt a slithering foot slide past. The brown-skinned man was rising to the surface to call for help. “X” clutched again, warding off the knife blow that swung down at him. A grim foreboding told him that this was to be a battle to the death.

He clutched the man’s arm again, struck with his fist under water, felt his knuckles hit yielding flesh. But the water deadened the force of his blow. The Malay suddenly wrapped muscular legs about him. It was like being caught in the tentacles of an octopus. Breath bubbled from the Agent’s compressed lungs. Nothing seemed able to break the brown man’s viselike grip.

“X” drew the Malay’s knife arm downward and held it, twisting slowly, turning the knife blade inwards.

The Malay’s body stiffened suddenly. For seconds “X” could not understand it, could not understand the strange shrinking movement the man had made. For the knife blade had barely touched his flesh. Then he felt the brown-skinned killer’s muscles growing lax. Strangely the man’s struggles were beginning to cease.

They rose to the surface slowly. Then the Agent understood and horror gripped him. The knife blade had been poisoned. The Malay had been struck with his own venomous steel.

The man was floating on his back now. A hoarse breath came through clenched teeth. He squirmed like a wounded fish, lay still. The man was dead.

For a moment only, the Agent hesitated, then his face grew grim. A swift plan came to his mind. Under the dim starlight, close to the water, he stared at the dead Malay’s features. Here perhaps was his one hope of saving Betty Dale. But it was a plan so desperate that it seemed like a challenge hurled into the very face of death.

Turning suddenly he began towing the corpse of the Malay toward the mainland’s shore. It was slow work against the river’s current. The bobbing head of the dead man behind him touched gruesomely against his back. But fear for Betty Dale overbalanced all else. These were not ordinary criminals. They seemed the spawn of some wild nightmare — a horror horde under the control of a ruthless fiend. They could not be combated in any ordinary way. The police could not help him. To tell them where the island hideout was, would, he felt sure, bring hideous disaster on Betty Dale. The green-masked devil would vent his fury upon her.

HE reached the shore five hundred feet below the spot where he had moored his boat. Lifting the lifeless Malay to his shoulder, he carried the man through the sparse woods, laying him at last in the bottom of the boat. Then “X” cut loose and let the current drift the craft downstream.

Not until the island was a half mile behind did he start the motor. Then he headed for the opposite shore, giving the island hideout a wide berth. His eyes were gleaming now. The plan he had conceived was built on desperation. Showing no lights, he sped back along the course he had come. His eyes strained across the dark water until he saw a small river town ahead.

He passed it, tied his boat under the black shadow of a sandy bank, and walked away from the river. He was fighting not only for Betty Dale’s life, he was fighting for the safety of his country. If he did not conquer now, this green-masked killer would beat him in the final show-down.

Without compunction then, the Agent acted swiftly. He must get the Malay to his own hideout. Wet and hatless, still in evening clothes, he knew that if a policeman saw him he would be held as a suspicious character. There would be questions, explanations, and time was vital. He prowled till he saw an auto stop before a house, waited till the owner got out, leaving the engine still running. In a second Agent “X” was behind the wheel, gliding off up the dark street.

He stopped by the river, transferred the body of the Malay to the car, leaving Foulette’s speed boat still tied among the trees. He was helping himself to other people’s property tonight. But there was justification for everything he did.

He sped along a road that edged the river, came at last to the suburbs of Washington, then to the city itself. The Malay’s body was slumped on the floor of the car. It would not be seen unless a policeman stopped him. That was a chance, too, he must take.

But he reached his hideout safely where Michael Renfew was still his prisoner. He doubled the Malay’s body up, wrapped it in a lap robe, and took the outside way to the hideout he had hired — the dark fire escape where none would see.

Once inside he set feverishly to work. There was no time to lose — not with Betty in the hands of the green-masked killer’s horde.

All the artistry of the Man of a Thousand Faces would be needed in the thing he planned to do. For long moments he studied the dead Malay’s face, studied its contours and its color, noticed the man’s clothes. The man was wearing a cheap cloth suit. Then “X” began one of the most difficult disguises of his life.

The high cheek bones were not hard to simulate. Strips of transparent adhesive pulling his own flesh did that. But the strange pigmentation gave him trouble.

Stripped to the waist he rubbed brown liquid into his skin, covering his whole torso. He had been in the water once. He might have to swim again. The coloring fluid he used was waterproof. But he carried a vial of liquid that would take it off.

IT was nearly an hour before his task was done; nearly an hour before Secret Agent “X” had turned himself into a brown-skinned savage. He found a suit in his own wardrobe like that the Malay wore. When he left at last, using the fire escape again, one of the green-masked murderer’s own men seemed to be emerging from that house.

Swiftly the Agent got into the car that he had taken in the river town, and went back along the route he had come. Not all the way, however. His eyes grew alert. He wore dry clothes now. They must remain so. If he arrived on the island wet it would mean suspicion, exposure, and the end of his desperate plan. But he could not go in the motor boat. He must have some silent craft.

He stopped at a place along the road where low-roofed buildings rose close to the river. They were dark, deserted, but the Agent walked quickly to them. Once again that night he helped himself — this time to a light canoe.

He broke into a boat shed, took the frail craft out, launched it. He was no more than a mile from the island now. The river current was with him. It would be better this way than going in the stolen car. Motorcycle police were probably looking for its license plates even now.

His pulses raced as the island loomed ahead. He sent the canoe forward under the swift thrust of his paddle. At the last he let it drift with the current.

Silently as a shadow it bore him forward. The dark vegetation of the island loomed before his bow. He brought the canoe in, waited breathlessly, ready to leap at the slightest sound. But none came, except for the faint stir of branches in the night wind and the lapping of the water.

The Agent was trembling as he set foot on land; trembling not for himself, but from the fear that filled him for Betty Dale. He drew the canoe up, turned his face toward the center of the island.

Each foot he moved he half expected to feel the prick of a death dart, or see a man with a knife leap toward him. Would his desperate disguise work?

The starlight shone through the branches on his brown-skinned face, revealing its Malaysian contours. His eyes probed the darkness ahead. Then he made a discovery. The building in the island’s center was no barn. It was an old storage warehouse, built at the time of the war, taken over now by a man who was a vicious enemy of society.

A dark figure moved suddenly at “X’s” left. He waited, pulses hammering, felt eyes upon him. One of the Malay killers came slowly up. Then he saw others, coming in from different angles. And suddenly his body grew rigid. For out of the darkness ahead came the faint, mysterious note of a deep-toned gong. It seemed to be a signal, summoning the dread clan together, and Agent “X” moved forward — into the very citadel of terror.

Chapter XV

HIS pulses raced as he crept close to that great gloomy building. His daring disguise had worked so far. He had not been questioned. He had been accepted as one of this poisonous Malay horde. But what of the gong? What did it signify? And where was Betty Dale?

There was one small door in the building ahead. Agent “X” entered this along with other of the brown-skinned men. A dim oil lamp burned at the end of a long passage. Boarding clattered underfoot, rousing ghostly echoes in this shadowed corridor. The odor of some strange incense deepened in the air as he neared the light ahead. Then the gong’s note sounded once more, closer this time, and the faces of the Malays around him seemed to change. They contracted into masklike immobility, eyes glittering strangely, heads stiffly held.

There was a doorway to the right of the dim lamp. One of the brown men opened this. A heavy curtain showed, with the glint of more light beyond.

Before entering this curtained chamber the Malay lifted a mask of carved wood from a peg and placed it over his features. These were the masks the torturers had worn when Saunders had been slain. They hung like grinning skulls upon the wall. Agent “X” took his.

Then the man ahead thrust the curtain aside. Agent “X” followed him, and felt a sudden pulse-beat of excitement.

In those few steps along that dark corridor and through this curtained doorway, he seemed to have been transported to a world fantastic as a nightmare. It seemed impossible that he was within a few miles of Washington, D.C., America’s capital.

For the scene before him was barbaric, amazing. The room, one of the ground-floor chambers of the old warehouse, was hung with the skins of animals and bright, Oriental tapestries.

Oil lights flamed and flickered around the walls. At the end of the big room, on some sort of wooden base, a hideous idol rose grotesquely. From its flaring nostrils streams of incense vapor rolled in slow spirals to the ceiling, as though the idol were breathing fire. It had huge, batlike ears, a long nose, wide-open, staring eyes.

Before it was an altar made of a slab of stone, and upon this a live sheep was tied. The note of the gong sounded again, muffled, mysterious, seeming to come from the idol’s very mouth.

The Malays, moving forward in the manner of sleepwalkers now, arranged themselves before the idol in a worshipful semicircle. There was a pungent odor mixed with the incense. Agent “X” recognized it as Bhang, or hashish. The leader of the Malay group passed cigarettes filled with the same drug. The men began to smoke, their eyes glazing as they puffed.

The frightened sheep at the altar let out one quavering baaa. In that high-ceilinged room echoes came back like a fiend’s insane laughter.

Then suddenly the Malays commenced to chant. A strange, barbaric, age-old song of the jungle — a devil song that the high priests or bomors of Kelantan had handed down from father to son through the centuries. Brown arms and bodies swayed; the pulse-beat of savage rhythm rippled muscles like serpents’ coils.

Agent “X,” drawing sparingly on the hashish cigarette that had been handed him, watched the ceremony tensely behind his mask. The Malays seemed to be working themselves up to a pitch of ecstasy. Their chant rose in volume. Suddenly, at its height, the gong sounded still again, and the chanting ended in a long-drawn sigh. Then they prostrated themselves, arms stretched out, heads on the floor, and “X” from the corner of his eye saw why.

A trapdoor opened beside the idol. A tall figure appeared. A man with a weird headdress, ornamented with green plumes, and a robe of the same hue. A man with a mask more hideously wrought than any of the others.

He mounted a flight of steps slowly, seeming to rise out of the very earth, and not until he had reached the altar before the idol, did the Malays lift their heads. They gazed raptly then. The masked bomor addressed the evil spirits, turning first to the hideous idol, then to the men before him, then to the tethered sheep. Again the animal bleated, pulling back with braced hoofs against the rope that held it.

The bomor spoke in words that Agent “X” could understand.

“You have done well, O men of Kelantan,” he intoned. “The great god, Tuan, is pleased. You have taken jewels from the white devils. You have laid them at the feet of Tuan. You have killed white devils, and this also pleases Tuan. Soon we shall take a boat across the water. Soon we shall return Tuan to his native land and he will reward you for the precious things you have so graciously laid at his feet.”

The green-robed priest then walked slowly toward the idol, lifting a cloth pouch from his belt. He thrust his hand into this, drew forth a glittering collection of jewels, and solemnly dropped them at the idol’s feet. A few sparkling necklaces he slipped over the idol’s upraised arms.

THE Malays around “X” chanted again, strange words that formed a jewel song. The eyes of Agent “X” gleamed behind his mask. Here, apparently, were the jewels stolen in Washington over a period of weeks.

His eyes riveted once more on the high priest. The man’s mask hid his face, but Agent “X” was certain that this was the one who had ordered Saunders’ death, the man who had killed Peters — and captured Betty Dale.

When the green-masked priest had finished decorating the idol, he turned and walked toward the tethered sheep. The creature was to be a living sacrifice. A strange chill of horror filled Agent “X” as the bomor stood above the animal, knife gleaming in his hand.

The song of the Malays to their devil god rose again, pulsed in the incense-heavy air with the slow, insistent beat of jungle tom-toms. At intervals the bomor’s hollow voice gave answer to the chorus.

The frightened sheep repeated its trembling cry, but was silenced by a thrust of the high priest’s knife. Briefly it struggled, then lay still. Crimson from its slashed throat stained the altar stone.

The ghastly ceremony was completed. Leaving the idol still glittering with jewels, the green-masked bomor backed slowly away. As he did so he committed the slain sheep into the hands of the Malays. The earth seemed to open up and swallow him. He disappeared as he had come — through the hidden trapdoor. The hideous idol had taken the sheep’s soul. Its worshipers had been given the animal’s flesh.

But the brown men were still under the influence of hashish. For nearly an hour they chanted. “X” had to remain. His thoughts were with Betty Dale — but to break that strange half-circle would have meant rousing suspicion.

AT last the chanting ended. The Malays rose, “X” among them. Each went first to the idol, bowed down, fingered the jewels. Agent “X” followed the example of the others, but when his turn came to bow he stared keenly at the glittering heap before him. Then he caught his breath, bent forward sharply.

These jewels were not real! They were cleverly made paste imitations. The green-masked high priest was tricking his followers, keeping the real gems himself.

The Malays seized the dead sheep then. They carried it out of the chamber into another smaller room. Here they removed their masks. Their faces no longer showed the rapture of devil-worshiping fanatics. They looked with brutish appetite on the sheep, and drawing knives from the wall they began cutting it up.

On a huge charcoal brazier they roasted the pieces and ate with savage gusto. Here were men who had been taught by their master to wear European clothes, but they were still savages at heart. There was something horrible about their ravenous, smacking greed as they fell upon the sheep. Again, as when they had snatched the jewels that evening, they reminded “X” of hungry vultures. But now the flesh they ate was real.

One by one they began to nod drowsily after eating. The hashish was still heavy in their blood. Their heads nodded. Sleep overcame them, stretched them out on the floor.

It was then that “X” rose and slipped from the room, ready to risk death to find Betty Dale. He knew that he hadn’t long. These men, closely resembling animals, would sleep like animals. In a short time they would waken. Any unusual sound would rouse them now.

Agent “X” stole into the room where the idol was. He examined the jewels for a moment, verifying what he had glimpsed. They were every one paste. He found the trapdoor through which the bomor had disappeared, tried to lift it. It was fastened on the under side. It must lead to some secret passage. The followers of the green devil god had probably never seen their bomor’s face.

Agent “X” hunted for another door. But there was none in this room. He went back into the smoky corridor where they had first entered. Here, a door led into another passageway.

Silent, tense, he began systematically searching every room of the old warehouse. He came upon one filled with rusty machinery, relics of the World War. Then at last he saw a faint light ahead.

He moved forward more stealthily still, pushed open a door, and caught his breath.

The light came from a smoky lamp. In its gleam a girl sat upright in a rickety old desk chair, bound hand and foot. It was Betty Dale, and at the same moment he saw her, her eyes riveted upon him and dilated with fright. Before he could stop her, or indicate who he was, her lips opened and she gave a piercing scream that echoed startlingly through the whole great building.

Chapter XVI

AGENT “X” leaped forward tensely, and as he did so he made motions in the air, indicating the letter X. He put a finger on his lips for silence.

Betty Dale’s face turned white as death. A great trembling seized her. She stared at the man before her with amazement. Agent “X” had come to her in many disguises, but never one seemingly as impossible as this. Her lips framed words, words that were almost a moan.

“My God — it can’t be! It can’t be!”

“It is, Betty!” The Agent’s voice was low, vibrant. He knew what catastrophe that one scream of hers might cause. She, too, realized. Her eyes held infinite remorse.

“I didn’t mean to — I was frightened. I thought—”

“I understand, Betty!”

The Agent drew a knife from his pocket, stepped forward, then paused. He was about to sever the ropes that held her. But quavers of her scream still echoed. A confused hubbub followed it. His worst fears had been realized.

“They are coming,” Betty said hoarsely. “Go quickly — before they find you here.”

The Agent meditated. He wasn’t afraid for himself. Long ago he had cast out fear. But Betty’s life depended on his own actions. If the green mask fiend discovered his real identity, Betty would pay for it in a way too ghastly to contemplate. If he freed her now there would be questions.

His mind worked swiftly. The hubbub in the building had grown silent now. The silence was ominous. He knew that sinister forms were running through dark chambers and corridors toward them. He came close, spoke hoarsely.

“They must not learn who I am, Betty. Everything depends on that. Scream! Scream again!”

“I don’t understand,” she whispered brokenly.

“You will. It is too late to try to escape now. Scream, Betty — now! It is the only way.”

The Agent’s orders were as law to Betty Dale. She trusted him. He had never failed her yet. She didn’t know what desperate plan he contemplated. But she screamed again loudly. The Agent raised his hands above her as though to clamp strangling fingers around her white neck.

“Again!” he commanded. “Scream!”

A second piercing cry tore from her lips. The brown men heard it. They plunged through the door, knives gleaming in their hands. They paused, animal faces intent on Betty Dale, who crouched as though in fear of the man before her. The Agent lowered his clawlike hands, cringed back, and stared at them.

The man who was their leader, next to the green-masked bomor, advanced.

“What is this?” he demanded in Malay.

The Agent did not answer. He made his body tremble. He did not meet the headman’s eye. Betty’s life depended on his acting now. He seemed a cringing Malay, caught where he should not have been found. When at last he spoke it was hoarsely, and Betty Dale started as the strange Malay words came from his lips — words unintelligible to her.

“This girl is one of the white devils,” said Agent “X.” “I was going to kill her.”

The headman looked at him sternly, doubtingly.

“Did not the great bomor say she was to be left alone?”

Agent “X” hung his head. The other continued.

“It was because of her beauty that you came here. Do not lie. You have gone against the vows of Tuan. You have sought the company of a white devil woman. You have sought company of one who is taboo.”

A fanatical light glittered in the headman’s eyes. He lifted bony hands toward the ceiling.

“Tuan, here is one who has broken his word to thee. Here is a foolish one who must be punished.”

BETTY DALE’S eyes sought those of the Agent. Words trembled on her lips. He silenced her with a movement of his hand behind his back. The Malay headman came forward, seizing Agent “X” by the arm.

“Come,” he said. “Leave the chamber of this white devil woman. It is for our bomor to make the decision of what shall be done with her. When the time comes to dispose of her, he will so order it. She will suffer — but the hour is not come. It is you who must suffer now. It is you who must die first.”

Die! The Agent was glad Betty could not understand. Her fear for him might have made her forget. She might have cried out. He walked quickly to the headman’s side. He bowed his face.

“I come,” he said. “I yield to Tuan’s will.”

He dared not give even a backward glance at Betty. His heart was pounding fast. He would rather die than have them learn he was not what he seemed. If that should happen, their fanatical, idol-worshiping fury would include the girl.

They led him back along the way he had come. The Malays around him set up a slow and terrible chant.

“The wrath of Tuan is mighty! O great is the strength of Tuan! Swift is the punishment of Tuan!”

The light of fanaticism spread to their faces, also. Barbarians under the skin, emotion swayed them. This man had broken his vow to the hideous green idol. This man must die. Agent “X” sensed the cruelty of innate sadism in their voices and expressions.

They drew the curtains aside, put on their masks again, and entered the chamber of Tuan. The great squat idol stared down, nostrils seeming to flare in derision. Its eyes glared as mercilessly as its human followers.

The voice of the headman came again harshly.

“Our bomor has gone back into the earth from whence he comes. We cannot summon him now. We cannot wait. It is the law that those who break their vows to Tuan shall meet swift punishment. The bomor would want it so if he were here. A faithful servant of Tuan shall see that the law is carried out.”

There was human ardor in the headman’s voice now. Here was a chance to act with the bomor away. Here was a chance to assert his own authority over the followers of Tuan, and to placate the idol as well. He made a sudden, imperious gesture. Agent “X” was seized. Before he could resist he was thrown on his face by four of the green-masked men. He heard the headman’s voice again.

“Bring cord, O followers of Tuan!”

Tentatively, the Agent struggled. But he saw the hopelessness of that. Knives were pressed against his back. The headman’s voice addressed him harshly.

“Act wisely and your death shall be slow. There will be time to make your peace with Tuan. Your cries will please him. But be a fool and you shall die by the knife swiftly, like a sheep that is slaughtered. You shall be cast among the lowest devils.”

Agent “X” lay still. But he made his muscles expand rigidly as they bound him; and he held them so, even though the Malays tightened the cords until they bruised and broke the skin. He held them rigid until his body was cold with sweat which his captors took for the sweat of fear.

Four of them lifted him to the altar stone before the grinning idol — the smeared slab on which the sheep had died. It was cold and wet with the animal’s blood. The Agent’s flesh recoiled from the contact. The headman’s next command came harsher still.

“The claw,” he said. “Bring that and the dust of Kep-shak. It shall be spread thinly that the man may suffer long.”

A Malay left the group. The others crowded closer. Brown hands ripped the clothes from Agent “X’s” chest and arms. His heart stood still. Would his dyed skin betray him? Would it stand the test? That for the moment worried him more than the threat of the terrible Kep-shak.

He did not wince when the claw-like implement was drawn across his skin, leaving its long crimson scratches. The Malays began to chant again. Weirdly their voices rose into the high-ceiled room. The headman led the macabre chorus, lifting arms toward the idol that stared down with glassy eyes.

“O Tuan, Great One. One who has broken faith with thee is now to die. Let his screams fall upon your ears. Let his groans make penance for the wrong he has done. Do not blame his sin upon those who have kept the faith.”

The headman himself took the metal box that contained the Kep-shak. He reached with clawlike fingers into it, withdrew a pinch of the grayish powder. There was a gloating light in his eyes, the lust of one to whom cruelty is natural. The other Malays stood tensely watching. Then the headman reached forward, raised his hands.

“Behold, O Mighty Tuan — the pollen of the flower of pain now falls upon the guilty.”

He opened wide his fingers, let the gray powder drift down onto Agent “X’s” skin and rubbed it into the scratches with a sudden vicious sweep of his hand.

Chapter XVII

THE tiny abrasions became like raw and throbbing wounds. A burning brand seemed to have been laid on them. Pain leaped along the Agent’s nerves. Pain reached into his body with twisting fingers of red torment.

As through a haze he saw the hideous idol and the faces of the Malays gathered round. The men set up a low chant. Their voices rose and fell, seeming to blend with the pulsing waves of agony that made a cold sweat bathe the Agent’s face.

He clenched his teeth, determined to stay silent. Then suddenly he changed his mind. They wanted him to suffer. They wanted him to suffer visibly. If he did not it would only bring more of the dread powder, diminishing his chances of escape.

He let a groan roll from his lips. The headman’s eyes glowed evilly. The Malay’s chant rose higher.

“Tuan, O Mighty One! Just punishment has come to him who wronged thee. Behold how he cries out in pain!”

The Agent groaned again, writhing in his bonds, gambling with hideous death, suffering agony that they might not learn who he was.

For seconds, while the grayish powder burned into his flesh, he turned and twisted, acting as he thought a Malay would. These brown men didn’t know with whom they dealt. They didn’t realize the Spartan courage of their victim.

At last “X” lay still; breath whistled between clenched teeth. The brown men nodded, as though pleased. The headman again addressed the idol.

“He is weak, O Tuan. It will not be long before the Kep-shak has done its work. It will not be long before thou art avenged.”

Agent “X” remained as if nearly dead, as if the astringent poison had already conquered his will. He let his mouth hang open, rolled his eyes.

Then his pulses leaped. The brown-faced men were moving toward the door. They thought him far gone now. They were going to leave him to suffer his last agonies alone, let the Kep-shak finish its deadly work. It was on this he had gambled. On it he had built a desperate hope. It was why he had chosen torture rather than death by the knife.

He watched the brown-skinned men withdraw. Pain racked his body. The sweat on his forehead was real enough. Blood beat in his temples like cruel hammer blows. The Kep-shak was seeping slowly into his bloodstream. A few minutes more and it would be too late. The powder had been sprinkled thinly, his torture slow, but human flesh and human will could not endure it long. He thought of Saunders, fettered and dying; of Peters, stretched dead on the floor of his cottage. Soon his own face would be like theirs.

But the Malays were going back to their sleep, back to their savage hashish dreams. “X” waited until their low-voiced chanting faded away.

Then he moved again. Not in pain-constricted jerkings such as he had allowed himself for the benefit of his torturers, but purposefully. Slowly he drew his right hand from the rope that seemed to press tightly into his flesh. The Agent had used a well-known trick.

By stiffening his muscles, holding them rigid when they bound him, he had increased the diameter of arms and legs. Now, as he relaxed them, they slipped back to normal size. But escaping from his bonds was not the most desperate part of his battle. That was the battle between the poison and his own iron will. A battle once more of flesh against spirit. For his limbs were growing numb. Pain wrenched his muscles.

When, after seconds of agony, his right hand was free, he loosened the ropes more quickly. Weak and shaking, he lay still a moment on the altar slab. Then he forced himself to his feet. His eyes were burning with a light that was almost feverish. He stumbled toward the curtained door; paused to listen.

There was no sound in the building now. But he could not go to Betty immediately. The poison powder was still on his arms and chest, being absorbed through the tiny cuts. “X” tried to brush it off, then stopped. At the first contact of his hand new stabs of pain thrust into him. But he must get rid of the stuff quickly, or die.

He followed the passage he had first entered, reached the small outside door, and slipped out into the darkness. His eyes would hardly focus. Breathing was getting difficult. Cold fingers seemed to be pressing around his heart

Through the night he staggered, stumbling, falling, getting up. He knew where he was going, but the way seemed endless. His knees were almost giving under him. His body was a quivering mass of pain.

Then he saw the glint of water. With a desperate plunge, he reached it, immersed himself in the river. Its chill was like a merciful poultice. He lay breathing hoarsely, till the poison began to thin as the powder dissolved. He moved his hands across the scratches now, washing the hideous stuff away; washing till each tiny abrasion was clean.

It was minutes before the pain began to abate. It was like the slow withdrawal of burning wires that had been driven into his flesh.

A HALF-HOUR passed. Then again he crept toward the building where he had suffered such torment. The poison of the Kep-shak had left his muscles weak. He didn’t let that stop him. Silent and tense he slipped into the building, crept along the dim corridor to the chamber where Betty was imprisoned. On the threshold he paused, looking in. Fear chilled him for a moment.

Betty’s Dale’s eyes were closed. Her face was pale as death. But she wasn’t dead. Her eyelids lifted at Agent “X’s” cautious hiss. Again he made the mysterious sign — the “X” traced in the air. In spite of this she almost cried out at the sight of his torn clothing and scratched skin.

“X” put his finger to his lips for silence, then drew a knife from his pocket. Quick slashes severed the ropes that bound her, and the Agent motioned Betty to follow him.

But the girl was unable to walk. She took an uncertain step across the floor, then sank down with a little moan.

“In a moment,” she whispered, “I’ll be all right.”

There was no time to wait. One of the Malays might take it into his head to prowl.

Swiftly Agent “X” stooped and gathered Betty in his arms. He was glad she couldn’t see his face, or the sweat that started on his forehead. The effort of picking her up brought gruelling pain back into his muscles. Half of his strength seemed to be gone.

With Betty in his arms, he moved stealthily along the shadowy passage. Once he thought he heard a sound and paused, tensely alert. Then he continued. Outside at last, he stood Betty gently on her feet. He rested a moment, breathing heavily, gathering his spent strength.

“I can walk now,” Betty whispered.

“Wait,” he said. “Later,” and picked her up again.

He moved straight toward the river, planning to skirt its bank. But a whisper of sound came from the building behind them. A human call! One of the Malays was awake!

The sound was repeated, taken up by other voices. The Agent’s blood seemed to freeze in his veins. His escape from the idol’s chamber had been discovered.

He turned and cut into the woods. Seconds were precious. He must locate his canoe. He dared not even think of the consequences if they were captured now.

In spite of Betty’s insistence that she could walk, the Agent continued to carry her. The ground was rough, with bushes and vines clogging the path. Everything depended on silence now. His own sure-footed tread, making their progress as quiet as was humanly possible in the underbrush, now and then rustled a leaf, snapped a dry twig.

There came a savage cry from the darkness behind. It was not loud, but held infinite evil. Betty Dale tensed in the Agent’s arms.

HE did not try to reassure her. Every breath, every ounce of strength he possessed must be saved for what he had to do. The canoe lay somewhere ahead where he had left it hidden under the river bank. His sense of direction had never failed him. He knew that even though his brain was still dazed by poison he was heading toward it.

But a tangle of vines impeded his way. They scratched his ankles, clutched at his feet and legs. He had to slow down. Once he tripped and, lacking the freedom of his arms for balance, almost fell.

There were definite sounds of pursuit now. Guttural grunts, low-voiced orders. Bushes rustled perilously close behind. It was like a ghastly nightmare, with the vines clutching at his legs like the fingers of an enemy intent on impeding his progress.

He broke through the mat at last, saw the gleam of water beyond. But the rustlings behind were coming closer. He put Betty down, found that she could walk, and took her hand. Then suddenly he thrust her ahead of him.

“Straight toward the water, Betty.”

He did not tell her why he made her walk ahead. But an instant later he ducked and thrust Betty Dale frantically to one side as something whispered by in the darkness with the thin hum of an insect’s wings. Their brown-skinned pursuers were shooting at them with poisoned darts.

Agent “X” saw the canoe, then, a slim dark shadow among the bushes. He drew Betty down, and they crawled on hands and knees toward the water. “X” shoved the canoe free of the slimy mud edging the shore, then whispered to Betty Dale to get in.

“Lie down,” he said, “flat.”

Betty obeyed. “X” seized a paddle, balanced precariously in the frail craft’s stern, and thrust strongly away from shore. The canoe shot out, sharp prow cutting the water with a knifelike sweep.

But as it did so, winged insects seemed to be following them. Horror crawled along the Agent’s spine as something plucked at his coat sleeve. There was a soft spat as a dart hit one side of the canoe. It quivered there, its sinister green-feathered end showing in the faint starlight.

Agent “X” glanced back toward the island, saw shadows moving along the shore. He dug his paddle into the water, and a powerful back-thrust sent the canoe shooting ahead. Then he, too, bent down, holding himself on braced hands that gripped the canoe’s gunwale.

Two more darts spatted into the canoe’s sides. Others hummed above his head. Then the current caught them, whirled the light craft around. He rose and sent it swiftly downstream.

But a cry rose from the shore. Another low-voiced order. A second later the Agent turned his head and tensed. Something was moving out from the island’s edge — something that lay black on the surface of the river.

Machinery whined. An engine barked into life. The dark shadow turned and glided toward them. The Malays had taken to their motor boat. Death was hurtling out of the darkness behind them.

Chapter XVIII

IT seemed that all the hideous forces of the night were conspiring against them. It seemed almost that the idol, Tuan, had the evil power attributed to him by his followers — and was reaching out fingers to snatch them back.

The Agent’s mouth was set. Pallor spread beneath the disguise he wore. His eyes were points of burning light. The motor boat behind them had turned now. It was plunging down the river’s channel in pursuit.

Muscles in the Agent’s back stood out like knots. He leaned forward at each stroke, dug in, sent the canoe shooting ahead under his paddle thrust.

“If there were only another paddle,” Betty whispered. “I could help you, then. You came to the island to save me.”

“I would have come anyway, Betty. It might as well have been tonight as later.”

There was a note of buoyancy in “X’s” voice. He would not let the girl know the fear he felt. She was being brave — as always — putting his safety ahead of her own. Under the faint starlight he caught the golden glint of her hair, saw her eyes, bright as stars themselves, turned upon him.

“They are coming,” she whispered tensely. “They must know now you are not one of them. They will kill you.”

“The fox knows many tricks,” Agent “X” answered, lapsing once more into the mysterious, indirect form of speech he was fond of. His eyes strained through the darkness. The shore was two hundred feet away. But if he turned, going side-wise to the current, he and Betty would be overtaken before they reached it.

Agent “X” thought quickly. The roar of the motor boat behind was like the pulsebeat of some drum of doom. Caught by the Malays again, he could not hope to escape. Neither could Betty. She would be taken back, and the green-masked criminal would make good his threat. She would be tortured horribly, and left paralyzed for life.

Breath hissed between the Agent’s teeth. He leaned over then, spoke hoarsely.

“There is one way,” he said. “You must slip out and swim to shore, Betty — while I lead them after me.”

He knew that Betty was an expert in the water. The river would hold no terrors for her. She could make the shore easily. But she made a protest that sounded almost like a sob.

“I can’t,” she said. “They will catch you — and kill you. Let me stay with you — and be caught — too.”

For a moment her words betrayed a secret of her heart; the secret that she felt more than friendship for this strange man; the secret that he had become part of her own life. Her eyes were misty. Her voice trembled as she leaned out and touched his arm.

“Let us fight — together,” she said.

The Agent caught the significance behind that word “fight.” Die was the word she should have used, the word she really meant. He kept the tremor from his voice as he answered.

“It is our only chance, Betty. And more than our lives is at stake. There is the work that brought me to Washington.”

“Then you swim!” said Betty eagerly. “Let me lead them off. They won’t hurt me if I am caught. They’ll just hold me prisoner till the police come.”

“X” didn’t frighten her by repeating the green-masked killer’s threat, but his voice was firm.

“No, Betty — we must both escape. And perhaps we can.”

He looked behind him, touched Betty’s arm quickly. “Now! In a moment it will be too late.”

A sound like a sob came from Betty Dale’s lips. She reached forward, drew her high-heeled slippers from her slim feet — the same slippers that had moved so gaily over the dance floor at Senator Foulette’s house a few hours before. She was still clad in evening dress, white arms and shoulders bare.

The Agent’s fingers touched hers for a moment, gripped them reassuringly.

“It will be all right,” he said. “But you must promise, Betty, to leave Washington at once.”

“Then how will I know — if you are all right?” she asked.

“Call the Herald as soon as you can. I’ll do the same. You’ll hear from Raphael Sancho. Now, Betty — good-by.”

The Agent leaned far over, bracing the canoe against his paddle. Betty Dale, slim and lithe as a nymph, slipped overside into the dark water. He saw her dive beneath the surface, saw her blonde head reappear twenty feet distant. For an instant that frightened him. What if the Malays saw her, too?

He swung the nose of the canoe around, paddled back, screening Betty’s movements. Then he swung again in the other direction.

A DARK shadow bulked on the river’s rim behind. He could see the speed-boat now. That meant they could also see him. His heart leaped with relief, for the other craft’s nose was turning. Betty Dale was safe.

He bent over his paddle. With Betty no longer in the canoe it seemed to leap over the water like a skimming bird. He dug the spruce blade in, gripping it in powerful fingers. He thrust savagely, turning toward the opposite shore.

The thunder of the speed boat crept closer. Death rode the wind behind, death in its most hideous form. But Agent “X” was fighting to escape; fighting the battle of his life. Now, with Betty Dale safe, he was free to pursue his strange work in Washington; free to continue his quest for the stolen plans.

But could he make the shore? The motor boat was plainly visible now. He could see the white froth at its prow, froth that was like foam flecking the mouth of a snapping, snarling beast. He was nearer shore than he had realized. The smooth surface of the river was broken by a mat of reeds — a marsh. Last year’s dry growth still raised thick stems. He could plunge among them and be hidden from the poison darts behind. But they were still a hundred feet away.

He swung his paddle to the other side, strained fiercely, cutting across the current. He calculated the best angle to make it, but still the speed boat was gaining on him. A guttural shout rose behind him. A strange chant followed. The Malays in the boat were singing their song of death.

They were sure of victory now; sure they would recapture him. But an instant later their chant turned to shouts of anger. They, too, had seen the dark barrier of reeds. The motor’s roar reached a higher note. It swept down out of the night like a savage demon’s growl.

Something struck the water close to “X’s” canoe. For an instant he saw a tiny feathered stick before it sank out of sight. A dart! The high wind had made the Malay’s aim poor. He must gamble now — on the wind, to send the darts wide of their mark; on the reeds ahead, to shelter him.

His lips were white as he swept forward over the last fifty feet of dark water. The thunder of the speed boat-beat in his ears. A dart sang past his head, buried its deadly point in the canoe’s gunwale. There was a spat against his paddle, and, looking down, he saw another quivering in the soft spruce.

A swish and the canoe’s bow slipped in among the reeds. Thick stems closed in behind it. For a moment he was safe from the flying darts, protected by a mat of vegetation.

But he leaped from the canoe, floundering ahead toward boggy land. And as he moved, the speed-boat lunged in amid the reeds also. Agent “X” lurched sidewise, heard the boat’s sharp prow crunch against the canoe’s frail side.

Swiftly, determinedly, he plunged ahead, deeper and deeper into the reeds. Dry stems cracked and broke. He was making noise, but the speed-boat’s throbbing motor drowned it out. Let them follow if they wanted! He had a start now. His own legs would be as fast as theirs. A great purpose spurred him on.

The speed-boat’s engine slowed. He heard the suck and slap of its propeller as it backed out. Then he stiffened. Raising his head, he sniffed the air, then turned startled eyes behind. In that instant new horror clutched his heart.

Between the thick reed stems he saw a faint glow. It brightened. A slim flame shot skyward. Above the speed boat’s throttled motor rose a vicious crackling sound.

Fire! The Malays had put a light to the dry marsh reeds! And the wind was sweeping off the river toward him!

Like an evil ghost a gray cloud of smoke drifted overhead. It seemed to spread huge arms above him. It was torn, thinned by the wind, but more followed it. Then the first glow became a crimson, blazing light. The speed-boat’s motor ceased. Across the still river, above the crackling hiss of flames, the death chant rose again.

“O Tuan, Great One, the gods of fire have aided thee in thy wrath! He who is guilty shall be punished. He shall be consumed in hot flames.”

As the strange chant rose, the fire seemed to spread its hungry arms. It leaped along the river’s edge and swept forward toward the spot where Agent “X” was floundering. And each instant the threat of its red fangs increased.

Chapter XIX

HORROR constricted Agent “X’s” throat. The crackling flames seemed to sound a death knell to the victory that had been so near. This was a peril he had not foreseen. Had the devil god, Tuan, won after all? The deepening smoke clouds seemed to form a curtain lowering upon the defeat of Agent “X.”

He turned fiercely and floundered on through the marsh. But he could not outdistance the wind. It drove the flames coiling through the dry reed stems like red, hungry serpents. The fire gathered fury with every foot it covered.

The Agent came to a hummock of hard ground. On his toes, he stared forward across the marsh. He groaned. As far as he could see, the waving tops of the dry cat-tails continued — an undulating plain, lurid now with the red glow of the fire.

A billowing breath of smoke swirled about him. He choked, stumbled on toward a slight break in the reeds ahead. Here he sank waist deep in the water. A channel cut through the marsh at this point.

He started to climb out, turned back. The roaring of the fire had shut out the Malay’s chanting now. The Agent was alone in a world of smoke and flame. Only a thin barrier of reeds stood between him and a blazing inferno. The flames were fast devouring that. On each side, where the reeds were thinner, arms of the conflagration shot out. He was being encircled in a fiery embrace — an embrace of death.

The water in which he stood was his only hope — and the Agent’s mind flashed back. Years ago, as a boy, he had been caught in a forest fire. He remembered how he and an old woodsman had saved themselves.

With quick tense fingers the Agent drew his knife. He bent forward, slashed at the reed stems, drew one out. With his knife blade he trimmed the ends. The reed was hollow. He put it to his mouth, drew air through. A grim smile made his eyes grow bright. A human life hung upon that slender reed — and a nation’s destiny, perhaps.

The fire was close now — thirty feet. Clouds of hot air swept forward. The Agent wet his reed in the channel’s water, then lay down on his back. Raising himself on one elbow, he kept his face above the surface of the water.

The fire swept onward in a roaring, red glare. Reeds on the channel’s edge began to smoke and curl. The top of one burst into flame, dropped as the stem bent and broke.

Heat quivered above the water. Blazing stems and gray ashes hissed as they fell. Then like a red, destructive wave, the full force of the fire advanced.

The Agent wet his reed again, put it between his lips. He lay flat, submerging his face now, sucking breath through the hollow stem. He opened his eyes. Water made his gaze blurry. But overhead all was brightening. The red glow intensified to orange. Wavering arms of fire swept across the channel.

Smoke beat down. The Agent drew in a lungful through the reed and choked. Terrible seconds followed in which it seemed nothing could survive that flaming holocaust. Acrid smoke cut his lungs like knives; the water above his face grew warm.

But the reed stems were consumed quickly. When it seemed that he could no longer live without a breath of clean, cool air, the fire glow began to fade. The air he sucked down through the reed became purer. At last “X” raised his head.

The channel now was rimmed with coals. Reed roots still smoldered. Powdery white ashes sifted down. He could hear the fire behind him, still roaring downwind. But he was alive. He had beaten Tuan again.

Far off across the river, he heard the chanting of the Malays. He could not make out the words, but he knew they must be reciting a victory song for the devil god. They believed “X” was dead.

He waited till even the ashes of the fire began to die. Then he rose from the channel that had saved him. Slowly he followed in the charred wake of the fire. There was danger that he might be silhouetted against its glow. Bnt he took that chance. The Malays were probably too far away to see him.

He must get back to Washington now. He must learn all that happened at the raid. The green-masked devil priest had told his followers that they would soon take a ship across the water. Did that mean he had the plans?

Fire was still burning far back along the marsh. There might be other channels and deep bogs to cross. The Agent walked parallel with the river, then turned downstream. A half mile below the spot where his canoe had landed, he again approached the shore.

After the hot fire a long swim held no terrors. He slipped into the cold water and struck out. Long swift strokes brought him at last to the farther side of the river. Somewhere here Betty Dale had also landed.

He followed the river shore upstream for a mile, passing the sinister island which lay peacefully beneath the starlight now. The Agent continued to the spot where he had moored Senator Foulette’s speed boat. Here was a ready means of getting back to the city. The thundering roar of its motor woke echoes along the dark river. The blast of cold night wind cleared the Agent’s faculties. His eyes were alert as those of a hunting hawk as he sped up the dark river toward the nation’s capital.

THREE quarters of an hour later a swift roadster turned into the driveway of Senator Foulette’s estate. A nattily-dressed army officer was at the wheel, an officer with the insignia of General Staff upon his collar. Papers in his pocket bore the name of Captain Stewart Black. The Agent had gone to his hideout and made a quick change in his disguise.

It was one-thirty, yet lights still showed in the senator’s big mansion. Sleep was impossible in that household where crime’s black shadow had so lately fallen. Washington’s greatest jewel robbery had taken place — and more. Inspector Clyde had men still stationed on the spot. The Foulettes’ servants had been grilled for hours.

The Secret Agent quickly parked his car beside the others in the drive. His eyes were penetratingly bright. There were things he must learn quickly. What conclusion had the police reached? What had been the aftermath of the brown-skinned Malays’ raid?

A group of reporters were congregated on the porch. No longer allowed admittance, they waited, hoping for fresh developments. Their cigarettes made red pin points in the darkness. Agent “X” walked swiftly toward them. Here was as good a way as any of learning the facts.

He spoke abruptly, playing the role of brusque and hard-boiled army officer.

“What’s going on here?”

Silence followed his inquiry. Then a chuckle sounded.

“Where have you been, general?”

“I know there’s been a robbery,” said “X” impatiently. “But tell me about it. I’ve just arrived in the city.”

“Robbery’s right,” a reporter said. “Enough sparklers were lifted tonight to cover a circus queen’s wedding dress. But that ain’t all! A guy and two janes has disappeared. There’s a mystery a mile wide and twice as high. The police are playing left-handed poker with stacked cards. This will be hot copy for a week.”

The reporter’s colorful description brought more chuckles from his comrades. But Agent “X” tensed with interest.

“Three people disappeared? Who were they?”

“A senator’s daughter, her girl friend, and a spik named Sancho. It looks like some guys were going into the wholesale kidnapping racket.”

“What senator’s daughter?”

“Old man Blackwell’s. The crooks knocked everybody out with giggle gas. They took the janes and the spik along with the rocks they lifted. But we ain’t got nothing out of Blackwell. He’s been hit hard and won’t open up. His dopey son was bumped off tonight, too.”

“What — Ferris?”

“Yeah, you know him? Sorry if I made a break, general. But he was parked at a sanatorium where they hand out cures to snowbirds. A nurse heard him screeching and thought he had the D.T.’s. She got a doctor. His door was locked and when they got in he was all scratched up and dead.”

The light of interest in the Agent’s eyes became like a snapping flame. “Scratched up?”

“Yeah! And a guy in a green mask was seen making a get-away. The same guy, I guess, that bumped off Senator Rathborne’s hired man last night. The bird they call the ‘fiend killer.’ Tie that if you can! Washington’s getting as good as Chicago used to be. How do you figure it, general?”

The Agent didn’t answer. His mouth was grim. Suzanne Blackwell kidnapped and Ferris murdered! Both the work of the green-masked killer. There was strange significance in this. He asked another question:

“How do they know Miss Blackwell was kidnapped?”

“She was gone when the police got here. She ain’t been seen since.”

“And everybody else was here?”

“Yes — except them other two.”

“X” turned suddenly and strode back toward his roadster. The reporter’s voice drifted after him.

“Say, general, give a guy a break. I handed you a lot of dope. How about spilling something yourself?”

BUT “X” had reached his car. Gears whined. He spun around the drive and headed toward the street, without having entered Foulette’s house. He had all the information he needed at the moment.

“That bird’s got something on his mind,” the reporter growled.

How much, he didn’t know. The eyes of “X” were steely bright. Out of this night of horror and mystery had suddenly come a startling revelation. Behind the green-masked murderer’s actions, Agent “X” read a hidden motive.

He sent the swift car roaring through the streets, racing as though with death itself. Suzanne Blackwell kidnapped. She had not been taken to the island with Betty. That he knew. Where, then? And why had she been abducted? This, coupled with the death of Ferris, brought an abrupt, amazing theory to the Agent’s mind. It was like the answer to an algebraic problem suddenly revealed.

He slowed his speeding car at Senator Blackwell’s drive, whirled in. This time he didn’t steal across the lawn. He went straight to the big front door. Another car was there, one from headquarters. A trembling servant answered his ring.

“Who are you, sir?” the man asked.

“Captain Black. I’d like a word with the senator, alone.”

The servant shook his head.

“Inspector Clyde is with him now, sir. He’s given orders not to admit anyone else tonight.”

“This is important. I’m from General Staff.”

The servant looked doubtful but impressed. “Step in then,” he said and stood aside uncertainly. “I’ll ask him. Perhaps he’ll see you.”

The Agent waited in the big outer hall. Low voices came through a closed door beyond. The servant knocked, disappeared, then returned.

“He says he’ll see you, sir — in a moment.”

It was several minutes later that Inspector Clyde appeared, his face drawn and worried. The butler motioned toward the library door and “X” walked in.

Senator Blackwell was pacing the floor, his ruddy color gone. He seemed years older than when the Agent had last seen him. There were deep lines in his face. His eyes held shadows of haunting fear. His voice shook as he addressed the Agent.

“You’re from General Staff, Wilbur says. What is it, Captain Black? Be as brief as you can. I’m a worried man tonight. And Inspector Clyde is waiting. I really shouldn’t see anyone. You’ve probably heard—”

“Yes,” said Agent “X” quietly. “And I’m very sorry, senator.”

The older man motioned to a chair.

“Sit down, captain. What can I do for you?”

“First tell me about yourself. Your daughter has been kidnapped, they say; and your son—”

“Murdered,” said Blackwell harshly. “I’d rather not talk of that, captain, if you don’t mind. I’ve told Inspector Clyde all there is to tell.”

“All?” The Agent spoke the word abruptly. It seemed to have a strange effect on Senator Blackwell. He stiffened, stared at the Agent with sudden furtiveness. His eyes were alert, guarded.

“Yes — what do you mean?”

For seconds the Agent didn’t answer. His eyes, burning with an uncannily intent light met those of the senator.

“Just what I say, senator,” he replied at last. “There are things that the ordinary forces of the law can’t handle. Things so important to the country’s welfare that they must be accomplished in absolute secrecy.”

THE pallor of Blackwell’s face deepened. He tried to light a cigar, but the trembling of his hands prevented it. The Agent snapped his own lighter and held it out. Blackwell puffed, sat down heavily.

“I don’t understand what you’re talking about,” he said.

“Those plans of Doctor Browning’s ray mechanism that were stolen when Captain Nelson was murdered,” said “X.” There was a pause, then he added softly, “Also the kidnapping of your daughter and the strange death of your son. A connection is apparent there.”

Blackwell ran a trembling hand across his face. “The police are hunting for her now,” he said. “Every way out of the city is being watched. Every air line, every railroad, every boat pier. They’ll bring her back to me.”

“And your son’s death?”

“Horrible! But why are you harping on it? Do you want to torture me?”

“No,” said “X,” “not torture you. But I believe you realize, senator, that something greater than even the lives of your son and daughter is at stake. That something is the present welfare and future safety of our country!”

The senator clenched his hands, spoke huskily. “The theft of the plans was terrible, captain. I voted that they be destroyed. I was the leader of the opposition. Now I dare not think what their theft may mean — but what have they to do with my own personal trouble?”

Agent “X” leaned closer to the older man, eyes steady.

“A great deal, senator. Aren’t you perhaps putting your personal troubles above the welfare of your country?”

A sound like a sob came suddenly from Blackwell’s lips. “I love Suzanne, captain. They’ve taken Ferris. I can’t let Suzanne go, too. I must get her back! Nothing shall stand in my way!”

“What if I told you, senator, that the man who has her is utterly without scruple. What if I tell you he will play you false — even if you accede to his demands — as I believe you have already done.”

FOR a moment it seemed that Senator Blackwell might have an apoplectic stroke. His eyes shone like those of a cornered animal. His face was a ghastly hue.

“My God, captain! Who told you that—” His voice trailed off. He stared at “X” horrified.

“Correct me if I’m wrong,” said “X.” “Your son, Ferris, killed Captain Nelson and took the Browning plans. He wanted money to buy more of the drug that enslaved him. He was the thief and the murderer! Am I not right?”

It was seconds before the senator could find his voice. Then he nodded brokenly. “I don’t know how you learned this, captain! I never thought—” he broke off, struggling for control. “Ferris was a poor, mad fool. But it was the drug, believe me! It was the drug! He never would have done it otherwise. It was my fault for telling him about the thing beforehand. I shouldn’t have taken even my children into my confidence.”

The senator had admitted Agent “X’s” amazing accusation! He continued hoarsely: “Ferris didn’t mean to kill poor Nelson. That I know. He only meant to stun him — he told me so. When he found what he had done, he brought the plans to me and—”

The senator paused again, shaking like a man stricken with palsy.

“Where are they now?” demanded Agent “X.” “Quick, senator, tell me that.”

Blackwell’s voice was hardly audible. “If you had a daughter, captain, and she were kidnapped— If you never expected to see her again, unless— If I can only get her back! I’ll make any sacrifice! I’ll stand trial before the whole country. Let them impeach me if they want to. I was afraid of shame before — when Ferris told me what he’d done. I was aghast. I hid the plans, waiting for a way to return them. Then Suzanne—”

”You mean the Green Mask has them?”

Senator Blackwell wilted suddenly, seemed on the point of collapse. “Yes,” he said dully. “He came tonight and demanded them. I don’t know who he is, but he’d got the truth from Ferris — tortured the boy. Don’t look at me so, captain. I gave them to him! It was the only way!”

“And when did he promise to bring back Suzanne?”

“Tonight sometime. He wasn’t clear.”

A harsh, mirthless laugh came from the Agent’s lips. But he stepped forward, laid a hand on Blackwell’s shoulder.

“I understand, senator. Keep quiet about this. Say nothing to anybody. Nothing at all, do you understand?”

Agent “X” picked up his army cap. He turned toward the door — looked back as the senator’s voice rose.

“What are you going to do, captain? How can I save Suzanne? How can I be sure?”

“There is no surety,” said “X.” “There’s only hope. I’m going to talk to the inspector. I want to see him alone.”

The senator spoke in sudden panic. “You’re not going to tell him — about Ferris — and the plans? Wait — the police don’t know!”

“It’s something else entirely, senator,” said “X” harshly. “You may trust me — to keep silent.”

He strode through the door, crossed the hall quickly, and entered the drawing room. Inspector Clyde turned at sound of his step. His sharp face was palely set. The Agent nodded, spoke abruptly:

“We’ve met before, inspector. At Senator Dashman’s home, you may remember. I’d like a word with you?”

Inspector Clyde nodded surlily. His pride was ruffled apparently because the Agent’s visit had interrupted his own interview with Blackwell.

“What is it you want?” he snapped. “I’m a busy man tonight.”

AGENT “X” asked a blunt question. “When you reached Senator Foulette’s after the robbery this evening, just what did you find, inspector?”

“Jewels had been stolen and three persons were missing. Miss Blackwell, Raphael Sancho, and a girl named Betty Dale. We believe they were kidnapped.”

“Who called the police — the servants?”

“No — they were knocked out, too. A man named von Helvig called us — an attaché of the German embassy.”

“He revived first, you mean?”

“Yes, he was among the first.”

“And when did he leave?”

“After we’d finished questioning him.”

“Did you make a list of all those present, inspector?”

“Certainly, as a matter of routine. They’d been robbed and filed normal complaints.”

“Did you happen to talk to a Miss Lili Damora?”

“Yes, she’d lost a diamond ring valued at five hundred dollars. She was with von Helvig. Was she a friend of yours?”

“Yes, inspector, exactly. And I sympathize with her loss.”

Inspector Clyde shrugged coldly. “What’s a bit of a jewel compared to human lives. Three people were kidnapped, I tell you. We have every reason to believe they are in danger,”

The irony of the situation held grim humor. Clyde was talking to one of the supposedly kidnapped people now. But the Agent’s face was masklike.

“Thank you, inspector,” he said. “I appreciate your information.”

A sly gleam of curiosity came into the inspector’s eyes now. “You’re not trying to cast suspicion on von Helvig, are you? It doesn’t seem likely that a man attached to a government legation would be a jewel thief, does it?”

“It doesn’t, inspector. You are right. Thanks again, and good-night.”

Secret Agent “X” turned and strode quickly from the room. The light of excitement was in his eyes now. There might be nothing in what the inspector had told him; but again, there might. Von Helvig was a murderous criminal. He had been a ruthless spy, and he had been the one to summon the police. Suzanne Blackwell hadn’t been taken to the island. Where was she — and was von Helvig responsible for her abduction?

“X” went straight to the Hotel Wilmot and was told that von Helvig hadn’t been in all evening.

The Agent pondered a moment, then left the hotel and drove swiftly through the night streets again. This time he went to the fashionable apartment where Lili Damora had her suite. The doorman had long since gone off duty. Agent “X” didn’t announce himself to the sleepy-eyed girl at the switchboard. He walked past, ascended in the all-night elevator, pressed the bell of Lili’s apartment. But there was no answer to his ring. Seconds passed. He pressed the button again. Still no answer.

The Agent took his tool kit from the lining of his coat then and entered the apartment by deftly and silently picking the lock.

The place was dark and quiet. An inexplicable sense of eeriness hung over it. He turned on his tiny light, moved cautiously. The bed hadn’t been slept in. It was not even turned back. He went into the drawing room next, stood still a second looking about, them bent sharply forward.

The place was in good order, but something on the rug caught his eye. A dark, sinister spot that was crimson, and still damp.

He examined the rug carefully, eyes brightly alert. Another spot of crimson showed near the hall entrance. He passed across it, opened the door of a guest room, entered.

The bed there hadn’t been used, either. The room was spotlessly neat. But he noticed a slight roughed-up place on the carpet. Beyond this was the door of a clothes closet. The Agent moved forward, touching the knob. It was locked.

With suddenly tense fingers, Agent “X” removed his compact tool kit again. He selected a steel implement to suit, forced the lock, and pulled the door open. Then he gave a sudden hissing exclamation.

A huddled figure lay on the floor of the closet. A white face with glassy eyes stared up at him above a crimson-stained shirt front. The face was that of Karl Hummel, alias Otto von Helvig, ex-Prussian spy and embassy attaché. One glance at his still, marble-pale features showed Agent “X” that he was dead.

Chapter XX

HERE was a turn of events as unexpected as a sudden blow in the dark. The Agent was staggered.

For tense seconds he stared down at Karl Hummel. One of Europe’s most cunning spies lay at “X’s” feet — dead. A man who had served his country during four years of bloody strife, outwitting many opponents, winning many triumphs. A man who had played the desperate game of espionage with all the strength of mind and body. And now, in time of supposed peace, he had succumbed to a criminal too terrible for him to cope with.

For a moment Agent “X” forgot Karl Hummel’s ruthless past — and saw him only as a victim of their common enemy. He felt a touch of sentiment for this brilliant old-time adversary of his, who had rolled the dice — and lost. Then he stooped and lifted Hummel up.

Stretching the dead man on the floor, he went through his pockets with swift thoroughness. Careful examination of a wallet in Hummel’s pocket disclosed a sheaf of bills, a few calling cards. “X” tossed these impatiently aside, then felt through the dead man’s vest. He paused to scrutinize another card. This bore the name of an undertaking firm — David Daniels Son. Unimportant, it seemed — or was it? The Agent stared at it for tense seconds.

There was gruesome irony in finding a mortician’s card in a dead man’s pocket. But there was no amusement in the Agent’s keen eyes. The murder of Ferris Blackwell, the kidnapping of Suzanne, had sent his mind leaping to conclusions which had been right. Now a macabre hunch was building itself about this bit of pasteboard in his fingers.

He left Hummel stretched out on the floor and went back into the hallway where a telephone stood on a small table. He dialed quickly, reading the undertaker’s number from the card. It was after two in the morning — but undertakers keep all-night phones. They expect calls at any hour. Death does not wait upon human convenience.

A voice answered at once. Agent “X” spoke cautiously.

“Von Helvig speaking. You delivered a casket this evening, I believe.”

Silence for a moment, then: “Yes — the delivery was made about nine o’clock — a hurry call. But Von Helvig wasn’t the name. There must be some mistake.”

“What was the name?”

There was another silence before the voice spoke again: “Hummel.”

The Agent’s body stiffened. His fingers gripped the receiver tightly. This must mean that Lili knew the spy by his real name.

“Karl Hummel?”

“Right.”

“My mistake. The same party wants some flowers. There’s been a mix-up. Will you please give me the address?”

“It’s out in the suburbs,” answered the voice. “But they’ve gone. They wanted to ship a body tonight. That’s why we had to rush the order through.”

“You did the embalming, too, I suppose?”

“No, another undertaker did that. We delivered the casket and called later to make shipment. They left by the Congressional Express.”

“Thanks! I’ve got to catch them if I can.”

The Agent’s voice was quiet. But his fingers trembled as they replaced the receiver of the phone.

Karl Hummel, alias von Helvig — the man who lay dead in the next room! A casket quickly bought and shipped by train. The Congressional Express. These were new and sinister angles in a mystery already bafflingly black.

Agent “X” looked at his watch. Already that train was miles away, speeding northward over night-shrouded rails. There wasn’t time to catch it by car!

“X” picked up the telephone again. The number he called this time was listed in no book, but at last a deep voice answered — the voice of the man known to the Agent as “K9.”

Briefly Agent “X” made a strange request. Then he plunged to the street and sent his roadster leaping from the curb.

Minutes later he braked savagely before the gates of Bolling Field. An air beacon still shone, but the field’s hangars were dark — all except one. Here sleepy-eyed mechanics were rolling out a ship. A two-place attack plane, high-powered, swift, dual-controlled. As mechanics whirled the prop a man slipped a flying helmet over his head — one of the army’s crack pilots.

He peered curiously as the man called Captain Stewart Black approached. Respect showed in his eyes when he recognised the insignia of General Staff. He saluted.

AGENT “X” scrutinized intently the man who was to fly his plane. “K9” had promised him a special pilot. This man who stood before him was Lieutenant Draper, an instructor in aerial acrobatics, a racer and dare-devil flyer. Here was a pilot as expert as the Agent himself.

“X” touched his arm.

“I’ve got to catch a train, lieutenant. The Congressional Express, on the Pennsylvania line. I want you to overtake her and land me.”

“Where?”

“On her.”

Draper’s face expressed amazement.

“You want me to land you — where?”

“On the train, I said. When you spot her, nose down and straighten out. I’ll manage the rest”

“You mean you’re going to transfer?”

“Exactly!”

Shaking his head doubtfully, but apparently realizing that it was no use opposing the will of his superior, the pilot climbed into the rear cockpit. He let the ship warm five minutes more. The life of a captain on General Staff might be on his hands tonight.

The swift ship zoomed up off the field and climbed like a rocket. Agent “X” slipped goggles over his eyes. His pulses seemed to beat to the radial engine’s roar. He knew the pilot thought him insane. But Draper could be trusted to do his stuff.

They wheeled over the city, headed northward, and picked up the line of the railroad within ten minutes. At twice the train’s speed the fast ship forged ahead. Mile after mile through the black night sky.

It was Agent “X” who spotted the Congressional Express first. There was a cut through the hills. He caught the glint of lighted windows, like a string of brilliants snaking along the earth. He turned his head and signaled the pilot behind him, motioning downward with one hand.

Draper’s face was white. But he obeyed instructions, diminishing altitude sharply and leveling.

The Agent rose in the cockpit, the windblast striking his body with the slapping violence of a huge palm. He stood poised until he grew accustomed to its thrust, then threw one leg over the side and stepped out on a wing. A tense calmness directed his movements — the calmness of a man who knows the safety of his country depends upon the success of his desperate plan.

He grasped the sharp struts firmly, slipped backwards and groped downward with his feet. His toes found the plane’s landing carriage. He climbed down, twisting his body around the strong steel rods. Six feet ahead the propeller cut like a gigantic scythe, death in its whirling blades.

The wind blast tore at him as the plane nosed down again. The ground billowed up. Lieutenant Draper, wild though he considered the attempt, was doing his stuff. He would have something to tell his buddies about, though they would undoubtedly think he was lying. His face was white as he bent over the controls, brought the plane down slowly, throttled the engine.

Plainly visible now, the train was almost directly below them. A rushing serpent in the darkness, with a brown top and a hundred fiery eyes glowing in its sides. It was toward that brown top that Lieutenant Draper flew, dropping the plane’s nose gradually, expertly.

Agent “X” clung to the landing gear, waiting tensely. Not till the train had rounded the curve and was on a long straightaway did Draper try to get close. Then he dropped altitude swiftly, leveled out a hundred feet above the train. It was a roaring monster now, flashing through the darkness at eighty miles an hour. Draper cut his own speed to match it, held steady.

Then, foot by foot, the plane seemed to drift down toward that gliding brown-backed serpent. Lieutenant Draper was peering over the side, goggled head thrust out, hands steady on the sensitively responsive controls. The train’s top crawled slowly back. A strong wind at their tail was making it difficult to synchronize speed.

A GRIM smile twisted the Agent’s lips. One slip — and it would mean death and the end. He must not fail now. He must wait till that backward motion of the train ceased. Fields, trees, dark houses fled beneath them. Draper came lower still until the ship’s air wheels seemed almost to touch a car’s top. And now the train appeared to be standing still. Its speed and the plane’s were matched. The moment had arrived.

Eyes steely bright, the Agent opened his fingers and dropped. For a second he seemed to hang in space between the roar above and below him. Then, on hands and knees he struck the roof of a car. He slid. The rushing wind pushed at him with hostile strength. For an instant he was helpless in its grip, nearly swept from the surface of the speeding train. Then his fingers caught in a ventilator opening, curled in a viselike grip. He was safe.

He crouched, looked up at the climbing plane. Lieutenant Draper’s goggled head peered over the side. His hand lifted in salute. Then the ship soared upward like a bird and vanished into the aerial blackness.

Secure, steady now, Agent “X” crawled forward along the top of the swaying car. He covered two Pullmans, a string of day coaches, came at last to the baggage car which was coupled to the tender. Steam and smoke from the big locomotive belched in his face, raining gritty cinders.

Thankful for the night darkness that hid him from the engineer up front, Agent “X” prepared for the dangerous maneuver that faced him. He must get from the roof of the baggage car to its forward end. Here was his only means of entering the car. Its rear was coupled with a closed-in hood to the express car behind.

He steadied himself for an instant on the swaying roof, near the front then sprang to the tender, grasping the ladder attached to its end. His pulses were hammering fast. This mad evening’s work was drawing to a climax. The jar and rattle of the plunging train made opening the locked door of the baggage car difficult. But finally he accomplished it, and a moment later was inside.

In the comparative quiet within the baggage car, a dim light burned. Trunks and suitcases were stacked along its sides. The Agent’s keen eyes probed. Then he started. A chill prickled along his spine. He had found the thing he sought — a coffin. But there was more than one. There were four!

“X” walked to them. Long, low, the four pine boxes held their cargo of the dead. Four bodies being shipped back to their homes. The Agent did a strange thing. Stepping back, he reached into his pocket. Certain things were always on his person — implements that aided him in his arduous work as hunter of criminals. Now he drew forth what seemed to be a small pocket camera.

HIS mind was working swiftly now. A wild theory had evolved in his brain. The coffin ordered by von Helvig, under the name of Karl Hummel, lay at his feet. One of the four pine boxes held that coffin. But which one?

Everything depended upon his find-out. If his theories were right, the coffin held a key to the whole mystery. He fingered the thing in his hands, drew a black cord from it with a circular disc at the end. This contrivance was not a camera, but one of the smallest, most sensitive sound amplifiers in the world. The disc at the end of the cord was a tiny microphone.

The instrument had aided him many times, but never had he put it to such a strange use.

Kneeling on the car’s floor. Agent “X” placed the amplifier’s disc on the nearest coffin top. The box containing the small dry batteries and the receiver was against his ear. He crouched like a ghoul, listening — listening for the heartbeats of the dead.

The roar of the train was a Niagara of sound. “X” turned the delicate rheostat dials, adjusting for selectivity. He heard the rumble of the wheels, the couplings scrape, but no other sound. The occupant of that coffin would be forever still.

Sweat beaded the Agent’s forehead. This was gruesome work, and fear gnawed at his heart — fear that he was perhaps too late — or that he had been wrong in his deductions. He passed to the next coffin. But his listening brought the same result.

His hands trembled slightly as he approached the third. He lowered the disc of his microphone, moved the dials. His amplifier was like a stethoscope now, and a sudden intense light brightened the Agent’s eyes.

Out of this wrapping of the dead came a living sound — the slow, regular beat of a human heart! A live person was in that gruesome box.

Swiftly the Agent straightened, thrust his instrument away. He walked to the front of the car. No one in sight. But the coffin was marked for unloading at Baltimore. And Baltimore was only a few minutes away! He must work quickly!

His tool kit disgorged a hacksaw of thinnest razor steel. With this he cut the nailheads in the outer box. He lifted the board free. Screws in the coffin’s top came next. Then he raised the lid and in the dim light stared down tensely.

A girl lay inside the coffin. She was inert, colorless. But her features did not show the marble rigidity of death. Her breath came with slow regularity. It was the unconscious form of Suzanne Blackwell.

QUICKLY Agent “X” lifted her from the coffin. He shook her gently, but she did not rouse. She was like a person under the influence of an anesthetic. Obviously she had been drugged. “X” rubbed her wrists and hands; he took a tiny hypo needle from his pocket and plunged it into her white arm. It contained a powerful stimulant — one of the Agent’s many secrets.

A minute passed — two. Then faint color began to show in Suzanne Blackwell’s cheeks. Agent “X’s” probing finger detected a quickening of her pulse. It was as though he had worked a miracle in the dimly lighted baggage car; brought a corpse back to life.

At last Suzanne opened her eyes, as “X” held her in his arms. He spoke gently, reassuringly, but the girl opened her mouth to scream. Awakened from her deep drugged slumber, she was like one roused from a nightmare.

“Don’t,” he said. “Be quiet, Miss Blackwell. You are safe.”

His hand covered her soft lips momentarily. Then he saw intelligence dawn in her dilated eyes. She stared up at him.

“Don’t be afraid,” he said. “It’s all right now.”

“Who are you?”

“A friend — a friend of Betty Dale’s. You’ve had a terrible experience, but you’re all right now.”

“Where am I? What has happened?”

“You’re on a train. You were — in this.”

Suzanne followed his gesture, gasped shudderingly.

“A coffin! Oh—”

“Listen!” “X” said tensely. “Criminals did this. They must be caught and punished. You can help me. Will you?”

She eyed him doubtfully, terror still in her eyes.

“Yes — if you are a friend of Betty’s—”

She could stand now, and her mind was fully awake. But she recoiled as her eyes discovered the other coffins.

“This is horrible,” she whispered. “It will haunt me — always.”

“It is horrible,” “X” said quietly. “But you will forget.”

He got into the empty coffin himself, under the girl’s amazed eyes. The train would soon be coming into Baltimore. There the coffin would be unloaded — and Agent “X” wanted to go with it. He must find out its destination. The fact that Suzanne had not been killed proved that she was being held as hostage in case of police pursuit.

He gave her quick instructions.

“Close the coffin. Then stay out of sight. Wait here in the baggage car or hide outside the end door if necessary. Get off when the train stops and run forward beyond the engine. Don’t let anyone see you. You might be taken prisoner again. Is it clear?”

“Yes,” the frightened girl whispered. “It is clear.”

The coffin’s lid came slowly down over Agent “X.” It was a big casket, meant for a larger person than Suzanne. “X” had plenty of room. And he would not have long to wait. Baltimore was only fifteen minutes away.

In the close darkness, vibrating with the rumble of the train, the Agent lay, his brain racing. If Suzanne did her part, all would be well. If not — but that possibility he refused even to consider. This last move had been a desperate one. But he could get out of the coffin whenever he wanted to. He had made sure of that. Only a few of the coffin’s screws had been replaced. They were sawed nearly through. The boarding of the pine box would be easy to lift.

But the air inside was strangely close. A faint odor came from the lining pressed against his face. He turned his head sidewise, breathing lightly in order to conserve the oxygen.

Minutes dragged by. The air grew more and more oppressive. It made him giddy. He fought against it, but he seemed to be back on Lieutenant Draper’s plane. He seemed to feel its lurch and sway.

Five minutes passed. Ten. The train was slowing down. Agent “X” felt drowsy now. He shook himself sharply, then tensed as air brakes hissed and a shudder jarred the train. He listened, identifying each sound.

THE express rolled to a stop. The door of the baggage car squeaked as it slid back. From inside the coffin, “X” heard the sound of men’s voices. There was the scrape of feet on boarding, the sudden sense of being lifted.

The coffin moved. A bump as it dropped, his oblique position, and the crunch of wheels on gravel told the Agent that he was now on a baggage truck, moving forward. Then the truck stopped and a moment of silence followed, until he heard the train get under way again, wheels screeching, engines puffing. Men’s voices came indistinctly. The Agent used his microphone once more. He’d planned this. It worked as well inside as out. But the speakers were only baggagemen.

An auto rumbled up. The coffin was moved again, carried to the auto, shoved inside. “X” realized he was now in a van. A long, jouncing ride followed.

It lulled the Agent dangerously close to sleep. He fought to keep awake. But his lids felt strangely heavy, and it was only the van’s squealing stop that roused him. A man spoke close to the coffin.

“Catch hold — easy now.”

The truckman’s voice, but it was answered by another that made the Agent tense suddenly, as it directed, “This way, boys — careful!”

He’d heard that voice before!

The coffin was carried forward, bumped down. “X” heard the soft wash of water, retreating feet. The coffin was stationary once more, but there was a rocking motion. Voices came from a distance, a woman’s among them. He could not distinguish words.

More minutes passed. Then came a pulsing roar of sound that almost split his eardrums. He quickly tuned the amplifier down. Listening tensely he identified the roar. Those were airplane motors. He was in a plane again! But that hissing slap of water against a hulk — it must be a flying boat or seaplane. The hissing stopped. He felt a long sweep upward, the dizzy rocking of the air.

More than ever now he was conscious of the stuffiness inside the casket. Lethargy seemed to have him in its grip. The microphone slid from his fingers.

Something warned him suddenly. Desperately he tried to rouse himself. But he slipped back. His throat felt dry. His tongue seemed huge in his mouth. The roar of the strange plane’s motors was like a roaring in his own head.

A tingling sense of horror spurred him to new effort — but no effort could rouse him from the lethargy now. He was slipping down — down — and he couldn’t move. Then at last the awful realization came into his numbed brain. There was a lingering drug inside the coffin — remnant of the drug that had held Suzanne Blackwell in its grip. But now it was too late. Agent “X” fell helplessly into a black pit of unconsciousness.

Chapter XXI

AGENT “X” awoke as from a terrible nightmare. He awoke with horror clutching at his throat. His mind was filled with a sense of appalling catastrophe. He had not anticipated the drug in the coffin. Luck had been against him. He had been outplayed at every turn. Now the last hand had been called — and he had lost. There was coldness on his face. The airplane’s engines no longer sounded in his ears. In their stead a voice was speaking. It was a taunting voice, harsh, inhuman as the scrape of metal. It was the voice of the man in the green mask.

Agent “X” opened his eyelids slowly. He was still lying in the coffin and fingers were poking at his face, exploring his disguise. Over him a man’s head hovered. He saw the startling hue of poisonous green. He saw lips moving; heard harsh words clearly now.

“This is a pleasure,” the green-masked man was saying, “and a surprise. I hope you have slept well — Elisha Pond. I hope your bed was comfortable. I hope you liked the trip.” A chuckle followed the words.

The Agent lay silent, too stunned to speak. This was no nightmare. It was reality more terrible than any dream.

“The coffin’s perfume — was it not pleasant?” the harsh voice taunted. “Very clever, Agent ‘X’! You gallantly rescued a fair lady in distress. But in doing so you got into distress yourself. Shall we call it that?”

The cold gray light of dawn shone in “X’s” eyes. He was staring up at the sky. He was on a ship’s deck. Still he did not sit up. He was seeking to clear from his brain the fumes that had knocked him out. The green mask’s voice continued.

“It has been an exciting game, Agent ‘X.’ I appreciate the clever moves you’ve made. You freed your blonde friend from the island. You gave my Malay colleagues a pleasant chase. Even when they thought they’d burned you, you had the laugh on them. And then — just how did you trace the coffin? That would be interesting to know. Perhaps you’d like to tell me.”

The man laughed again. “You can afford to talk now. The game is ended. You have lost. We can chat like old friends, until—”

The laugh that came now was as sinister as death. Looking into those eyes behind the green mask Agent “X” read his doom. But before he could speak another voice sounded — a woman’s voice close by. The Agent swiveled his eyes and saw the sinuous dark form of Lili Damora.

“Don’t trouble him, Ito,” the woman from Budapest said. “I can tell you how he traced the coffin. He found Karl Hummel in my apartment. It was my fault. I forgot about the fool’s having that undertaker’s card.”

The green-masked man bowed. “Very pretty, Agent ‘X.’ Your deductive faculties are good. You played me closely all the way. How unfortunate that in the end you were one move behind!”

“Don’t gloat, Ito,” Lili Damora admonished. “It is such frightfully bad taste.”

“But it pleases me to vanquish a worthy adversary,” the green-masked man replied.

Secret Agent “X” stared keenly now. “Ito,” Lili had called Green Mask. That was Japanese! “X” spoke for the first time.

“You were in doubt, too, about the plans until you tortured Ferris Blackwell.”

“But I hit upon the truth at last. And you are still in doubt.” The green-masked man laughed with grim amusement. “Is it not a pretty game, Lili? Let us show him how very close to the plans he is.”

Green Mask clapped his hands. Like sinister wraiths, four brown-skinned Malays moved out of a hatchway and glided up.

“Get up,” Ito said to Agent “X.” “You see where you are — on board my ship. And I have my friends with me. You know their tricks by now, I think.”

Agent “X” rose slowly. He saw the Malays facing him, knives in their hands.

“Perhaps,” said Ito, “I can’t convince them that this is the man who cheated their god, Tuan. Your disguise was too good for that. But they will be glad to kill at a word from me. Let me show you now where the plans are.”

ITO crossed to the coffin that “X” had vacated. He reached between the lining and the frame, drew out a long envelope. He held it up an instant. Then he shoved it in his pocket.

“I was careful to the last, you see. I paid a compliment to your secret service. If I should be caught I didn’t want the plans found on me.”

The Agent adopted the same suave manner as Ito now.

“And what do you intend to do with me?” he asked.

“Compliment you still further,” said Ito. “Flatter you with death. If you were not so clever I might let you live. But I shall be courteous. You may choose one of several ways. You had a taste of Kep-shak. Would you like to complete the experience?”

Lili Damora shivered slightly and spoke with a note of contempt.

“Can’t you be civilized, Ito? Why not shoot him as I shot Otto? It is so much easier and quicker.”

The green mask turned on her quickly.

“Did I ask for your advice, dear lady? You know how I hate Americans. And I have a right to speak since my father was one. Don’t try to cheat me of my fun. If you don’t like my ways go below!”

Lili Damora flounced off and Ito laughed. The cruel bantering note was still in his voice.

“Choose,” he said. “How do you wish to die?”

The eyes of Agent “X” roved desperately — roved over the cold morning sea, over the faces of the men around him, along the deck of the vessel he was on. He was searching for a way out. And his mind told him there was none; his mind told him he was beaten.

How did he wish to die? This fiend was calmly asking him that. Death held little terror for Agent “X.” He had been schooled against it. But defeat in this, the greatest thing he had ever undertaken, was a bitter, ghastly pill to swallow. Worse even than the sting of the Kep-shak torture. His country, his chief in Washington relied on him — and he had failed. This masked criminal was sneering at him — this man who had the Browning plans. Revolt flared in the mind of Agent “X.” His eyes turned upward, and suddenly he tensed.

Thin, ghostly wires stretched across the sky between the vessel’s masts — wires that were his last link with the world he knew. Radio! This was a tramp steamer he was on. He’d seen the type before and knew them well. His eyes dropped. He was silent for a moment. Suddenly he raised his hand.

“Look! Over there!”

It was an old trick. He was pointing out across the sea. But he was counting on its very simplicity to fool the man who used elaborate tortures on his victims. He would not suspect “X” of using a ruse so crude. Moreover, Ito was swollen with the feel of victory — arrogantly sure of himself. Agent “X” had calculated well. At his sudden gesture, the tenseness in his voice, Ito and the Malays turned their heads.

IN that moment, Agent “X” leaped. He heard the shrill cry of anger that lifted behind him. A knife whistled through the air. He sprang aside. The knife hissed close beside him, landed with a thud against the deckhouse.

He sped forward along the vessel’s deck. A desperate plan had formed in his mind. He climbed an iron ladder, ran ahead. The bridge rose before him. He found the door he wanted, burst in. A man who was not a Malay crouched over his instruments in the ship’s radio room. A man who was a weak-eyed river rat. A white man, but a man enslaved by drugs. One of Ito’s craven slaves.

The Agent closed the door behind him. He barred it with a chair. His fist flashed out, crashed into the face of the wireless man. The man slumped to the floor, head lolling.

For a bare second the Secret Agent paused. He studied the dials along the wall, the complicated instrument board. He threw a switch, leaped to the small table where the man had sat. His fingers touched the radio key.

Quickly, expertly, he gave the signal of the Hampton Roads naval station. Seconds that seemed eternities went by. Then there came an answer to his call.

Shouts sounded outside now. Running feet. The Agent paid no attention to them. Bent over his key, eyes burning, he sent a message that might influence a nation’s destiny. For three minutes he used a secret naval code, then stopped. Men were beating on the door.

He switched the light off as evil faces were framed in the wireless room’s small window. The glass broke behind him with a crash.

The Agent leaped across the floor. There was another door beyond, an officer’s room. He ran through this, out to the deck again, doubling back along his tracks. A Malay saw him and gave a howl. “X” plunged into a doorway, down into the interior of the ship.

Death stalked on all sides of him now. But he must fight for time — time. Where was Ito now? “X” didn’t know. He ran forward to the cabin where Lili Damora had gone. A Malay appeared in his path, knife gleaming. The Malay hurled the knife. “X” dodged and fired his gas pistol into the man’s face.

Then he saw a door ahead of him and flung it open. A woman’s piercing scream sounded. Lili Damora stood before him.

“You!” she hissed. A gun appeared in her hand. The Agent sprang aside as it lanced flame. He leaped forward tigerishly, wrenched the weapon from her fingers. She cowered back.

The Agent’s lips curled. Here was the creature who had been playing with the green-masked criminal all the time. She had even used Karl Hummel, outwitted him, and slain him when he was of no further use. The Agent read the whole ghastly story now. Karl Hummel in her hands had been a mere tool.

“Go to the door and lock it quickly,” he ordered.

She obeyed, sliding a heavy bolt home. “X” knew the door had iron cleats across it. It and the room’s partitions formed a stout barrier.

As Lili stepped back a voice came through the wood — the voice of green-masked Ito.

“Clever again, Elisha Pond! You sent a wireless message. But even that is too late. This boat is fast. They will not catch us now. And if they should overtake us, we have a plane on board. Long before help can arrive we shall have broken in — and you will be dead.”

“Leave him alone,” cried Lili. “He will kill me if you don’t.”

The green-masked man laughed.

“You are a dear lady, Lili. But let me make it clear that a threat to your life cannot save Pond. High as I hold you in esteem my enemy comes first.”

As though to emphasize this, Green Mask fired through the door, and the bullet whistled between Lili and Agent “X.” Then there came a series of thuds as Malays battered axes on the door.

Lili hissed like a venomous snake, furious that Ito was willing to risk her life to get at “X.” She turned to the Agent and a torrent of angry words came from her lips.

“I’ll tell you who he is,” she cried. “You’ll understand the sort of animal you’re dealing with. He’s a half-caste — a mongrel — half Jap and half American. Because his father deserted his mother she taught him to hate America.”

A shower of ax blows drowned out her voice for a moment. The door shook and creaked. Lili screamed above the noise so that her words would reach Ito’s ears, too.

“I hate him as much as he hates Americans. I’d like to destroy him as he would destroy them. I tolerated him only because he promised me wealth when the stolen plans were sold.”

Lili Damora looked like a sinister harpy now. Fury distorted her face, drove her beauty from her, seemed to add years to her age. She screamed a curse.

“Ito with his high-society airs! Ito who calls himself—”

TWO more pistol shots rang out as Ito fired furiously through the door. Ax blows half deadened their reports. But Lili stopped speaking and gave a piercing shriek. She clutched her left side, crimson staining her fingers.

“You’ve hit me — you devil! You’ve—”

The words choked in her throat. She took a staggering step forward, then collapsed and lay still on the floor — a murderess slain by her own partner in crime.

Whether it was intentional or not “X” didn’t know. He stood aghast, tense and silent as the Malays hacked the door to pieces.

Five minutes — ten — went by. Death would come soon now — death—

Then a new sound came, filling the air, rising above the ax blows. It was a sound that pulsed through the Agent’s blood, thrilled him. The roar of airplane motors — the planes the Agent had summoned by radio. They circled the ship, signaling for it to stop — but the vessel forged ahead. Then suddenly the Agent started.

There was a noise out on deck. The staccato rattle of a machine gun. This sinister craft was armed. He stared from an open port.

One of the planes, sweeping low over the gray sea, suddenly tilted, thrusting its broad wing toward the sky. A column of black smoke trailed behind it. Its engine coughed, sputtered. There was a blinding, rending flash of flame. The gray plane was torn apart before his horrified eyes, its gas tank hit and exploding.

The other navy planes rose higher. One of them swept down over the ship. Something black dropped through the air. It struck the sea close by. There was an explosion, a geyser of water. The Malays howled in fear. “X” heard the machine gun chattering again. Now was the time he had waited for.

He crept back to the cabin door, unlocked it. The arrival of the planes had taken the Malays out on deck. Ito was with them, urging them to fight.

The Agent charged across the deck, a bounding, leaping streak. Before Ito knew what was happening, Agent “X” had caught him in his arms. His swift charge carried them both over the rail. Thay went tumbling head over heels down into the sea. Malays lined the deck above, blowpipes in their hands, sinister darts ready. But they dared not shoot for fear of hitting their master.

The two below were locked together, but Ito fought like a trapped animal. In a frenzy at being defeated he scratched, kicked, and bit. His eyes behind the mask glared with inhuman hate. His fingers were like clutching talons as he sought for “X’s” throat. But Agent “X,” spurred on by the great cause for which he fought and with victory close at hand, battled with every nerve and muscle in him, battled — and finally won.

As in a daze he saw the swooping gray planes overhead. A bomb struck the vessel’s stern. Flame leaped out.

Then one of the big planes landed on the water and taxied over to the spot where “X” held the furious Ito, now subdued. “X” pulled the green mask from Ito’s face — and was not wholly surprised at what he saw. The face before him was that of Sam Barkley — supposed American sportsman — the man who had pretended to be an ardent suitor of Suzanne Blackwell’s. It was from her no doubt in some indirect way that he had finally guessed the truth about Ferris.

The Agent’s hand reached into Barkley’s coat, drew out the Browning plans and transferred them to his own pocket. They were wet; but the water-proof ink wouldn’t run. The plane came up and stopped. It was a big naval amphibian.

“Ahoy there!” cried a voice.

THE plane carried a crew of four. Strong hands reached down for Agent “X” and Barkley; but, as they did so, one of Barkley’s arms moved suddenly. A gleaming vial was in his fingers. Before “X” could stop him he put it to his lips, pulling out the cork with his white teeth. With a movement swift as lightning he swallowed the vial’s contents, made a choking sound, then gave a strange, harsh laugh.

“X” smelted the fumes of bitter almonds — prussic acid.

The scared men in the plane swore fiercely and yanked Ito up. But they were too late. Barkley’s face was changing color. He coughed, writhed a moment, and lay still.

“What in hell does this mean?” one of the navy men asked.

“It means a master spy and murderer has committed suicide,” said “X.”

“And who are you?”

“That can wait until later.”

“We were told to go out and halt this ship, the Kelantan. She wouldn’t stop. She fired on us — brought down one of our planes. What were you doing then? How do we know you’re not a spy, too?”

“You don’t,” said the Agent quietly. He knew that, in spite of his army uniform, nothing he could say would convince them. There would be questions asked when he arrived on shore. They’d want to see his papers, find out how it happened that an army officer knew the secret naval code that had brought the planes out. He couldn’t afford to reveal his identity even though he now had the Browning plans. His career wasn’t ended yet. He was still Secret Agent “X.”

He watched breathlessly as the gray planes stopped the Kelantan with another well-placed bomb. The Malays ran for cover, their machine gun abandoned, but the ship was sinking by the stern, its bow reared up. It listed, water pouring through a gapping hole in its plates that the bomb had made — and suddenly it slid bottomward, air bursting through bulkheads and whistling up through the waves above. The Kelantan and its murderous crew were gone forever.

The plane “X” was on rose from the water, heading back toward land. There was a cabin in it. Two pilots sat up front. The flight commander began questioning “X” in the cabin. A member of the crew stood by. Sam Barkley’s body rolled grotesquely as the big plane lurched and dipped.

The gray shore line came out of the landward mist, then the plane sailed over Chesapeake Bay. But, to the navy man’s questioning, Agent “X” answered only in monosyllables. Then, as the plane began to glide downward, he did a strange and sudden thing. He whipped his harmless gas gun out, sent a puif of vapor into the faces of the two men in the cabin.

As they collapsed, Agent “X” reached above him and pulled a ’chute pack from a rack. He slipped quickly into the harness, thrust the side door open against the wind blast.

An instant he poised, then leaped, his tumbling body forming a black receding dot. It was a delayed jump. He didn’t want the other planes to see him, or, if they did, he wanted to be too far down for them to catch. He didn’t pull the rip cord till he had fallen nearly two thousand feet and the water was a thousand feet below him. Then his ’chute blossomed out. He had figured carefully, and the high wind off the sea bore him toward land.

Later that same morning a mysterious message reached the high Government official known in the secret files as “K9.” The message was in code. It was brief and to the point, and it came from a town near Baltimore.

“Browning plans recovered,” the message said. “All is well. On way.”

There was another sentence telling Department of Justice agents to go to a certain address in Washington. Fast cars filled with armed operatives hurried to the spot. There they found a notorious spy named Michael Renfew, a man the D.C.I. had long been wanting to catch because of his subversive espionage activities. They also found a dead Malay whose presence Renfew could not or would not explain.

At almost the same moment Senator Blackwell received a telegram which helped to lift the gray pallor of fear from his face.

“Don’t worry,” it said. “All is safe — and secret.” It was signed “Black.”

The senator had his daughter back now. She had arrived by auto; brought from Baltimore by friends of the family.

Silently, devoutly, Senator Blackwell blessed the name of Captain Stewart Black, the dapper officer from General Staff who seemed to be a clairvoyant and the very soul of discretion, all in one. He did not know that the man behind it all, the man he had to thank, was Secret Agent “X”—master of mystery, and man of destiny.