Secret Agent "X" – The Complete Series, Volume 4

Chapter I

LIPS tightly compressed, eyes clouded with growing horror, a man in a black press coupé knifed into upper Broadway. His hands on the vibrating wheel before him had the steely tautness of curved talons. His foot fed gas recklessly to the roaring motor. And in his brain beat the mad words of an amazing message he had received a few moments before.

“Come, boss! Hurry! It’s getting dark — dark as night. Dark as hell itself. I can’t see the sun any more — because it’s gone out. And all over the block, people are screaming, fighting — looting! Come — for God’s sake!”

The words had been uttered with the frenzied hoarseness of one gripped by terror of the unknown. They had transmitted some of their horror to the nerves of the man in the careening press coupé. And, incredible as they seemed, he couldn’t ignore them. For that message had come straight from the lips of an operative trained and employed by one of the shrewdest criminal investigators in the world.

Others evidently had received word of this madness. On all sides of the rocketing press coupé was movement, turmoil, a frenzied medley of sound and action as the city stirred itself into unwonted activity.

Near by, an emergency squad truck, siren shrieking, hurtled forward like a berserk green monster trying to shake off the human leeches that clung to its swaying body. On an avenue running parallel, a clanging ambulance kept pace. Farther ahead, a regulation police prowl car added a persistent thinner note to the din.

Excitement was in the air. Excitement with an undercurrent of nameless fear, lashing the spinning wheels of a dozen vehicles to a more furious pace — as all raced forward toward the same objective.

But the man in the press coupé was making the best time of all. Hunched forward to the seat, tense in every muscle, he tore past intersections with the horn button held down. He drove with death-defying abandon; swung by the ambulance, cut in ahead of it, ignoring a cop’s whistle that shrilled at him to stop.

He took a time-saving detour through a narrow side street. This got him ahead of the police cruiser. Another five blocks, and he trod abruptly on his brake pedal and brought the coupé to a slithering, screeching halt. This was as far as even he could go. The street was blocked by jammed traffic and crowds of frightened human beings, milling, shouting, jostling each other.

As he leaped out of his coupé he heard snatches of conversation from the bloodless lips about him:

“The dark!”

“The terrible twilight!”

“The world — coming to an end!”

“The devil — is on earth!”

Superstitious fear showed on the faces of some. A woman was weeping hysterically, fearfully, wringing her bony hands in a paroxysm of awed fright. An old colored man who looked like a preacher was down on his knees at the edge of the curb, praying, his body swaying, his eyes rolling toward the sky above, his deep-toned voice quavering in religious fervor.

“Oh, Lord, save us! Save thy chullen from the hands of Satan! Save the blessed earth from his wiles and wickedness!”

His words seemed an echo of the stark terror that was stamped on the features of everyone in sight — terror of the unknown.

The man from the press coupé strode ahead grimly, slipping unnoticed through the milling mob, moving on toward the spot from which the nameless horror seemed to have radiated. And then he glimpsed one face upon which no fear was registered. It was the face of a white-haired, shabbily dressed beggar standing in a doorway with a tray of chewing gum tied around his middle — a blind beggar whose sightless eyes had mercifully been spared the horror of the darkness which had cast its dread spell over every one else.

The blind man leaned forward abruptly, listening to the approaching footsteps.

Suddenly he called out: “Mr. Robbins! Mr. Robbins!”

Only for an instant did the driver of the press coupé pause. He laid a friendly hand on the blind man’s shoulder, uttered a name quickly: “Thaddeus Penny.” Then he plunged on through the crowd which at this point had begun to thin.

A hundred feet from the spot where he had been forced to park his coupé, he came upon ghastly evidence that the mysterious terror which all had mentioned wasn’t imaginary.

Two big delivery trucks, coming out of side streets, had met in a fearful, head-on collision. The motors and front wheels of both were telescoped into a tangled mass of shattered junk. Water from their cracked radiators had spilled into the street, running away in rusty rivulets.

THE driver of one truck was visible. Yet he was hardly recognizable as a man. An inert, flattened figure, he lay pinned under the side of the cab — beyond the aid of ambulance or interne.

The man from the press coupé stepped jerkily around the telescoped trucks and moved forward. But the accident of the crashing trucks was only the beginning. Twenty feet farther on he paused to stare with widening eyes into the gutter. Here, too, the Grim Reaper had struck.

The bodies of four people, three women and a man, lay in distorted postures, trampled to death by the onrush of many frenzied feet, their clothing torn and soiled. Bundles they had clutched before the fear-crazed mob had wrought its horrible havoc upon them, lay scattered and broken. Then the coupé’s driver came to the most gruesome tragedy of all — a thing so horrible that it made breath hiss between his clenched teeth.

For a school bus, filled with small children, had swerved and crashed into a lamp post. It had cracked open down its whole length, and turned on its side, spilling the crushed and mangled forms of its small occupants into the street. Tousled curly heads and tiny faces lay still under a mass of broken glass and debris. Three who had succeeded in dragging themselves from the wreck had fallen, pitiful victims to the frenzied mob’s feet. Only one, a little girl with chestnut hair, had managed somehow to reach a doorway on the street’s opposite side. Huddled in a corner, she sobbed in confused terror.

The man from the press coupé walked to her, bent down and whispered quiet words of reassurance until her crying ceased. He picked her up, comforted her still further, and gave her into the temporary care of an old lady who was peering fearfully from a first floor window.

Something else attracted his attention then. Faces stared out at him from the glass front of a big store, men and women with fear shadows in their eyes, gaping like frightened, wondering animals, too dazed to move.

He strode toward them, opened the store’s door, and when he entered they backed away. But he raised his voice harshly, authoritatively, and began quick questioning. As he did so he drew a press card from his pocket and held it up for all to see. This bore the name of A. J. Martin.

The store’s proprietor was the first to find his voice and answer the queries that were flung at him. Yet what the man said seemed hardly to make sense, any more than the statements of the milling people at the edge of the mob. For he was trembling, his hand waving toward the littered street, and his speech came haltingly.

“The dark!” he croaked. “The dark — out there! Even our lights were no good. The sun must have gone out. It was — an eclipse, I guess. But I don’t understand — about our lights not shining.”

A pause followed his startling words. Then a frightened woman spoke:

“No — you’re wrong. The sun didn’t go out. It was a fog — a black fog that filled the street. The people ran screaming. I saw them — and then — It was terrible — like a night when nothing can be seen.”

The man who held the press card nodded tensely. Fog, or an eclipse, or the falling of night — these people couldn’t explain the thing that had come to pass. Yet something infinitely strange had happened, something under the influence of which nightmare tragedies had occurred — cars smashed, men trampled, small children killed.

A moment of silence passed while his sharp eyes hovered over a dozen fear-strained faces. Then he said: “Thanks,” turned and hurried back into the street.

THOSE whom he had questioned weren’t aware that no syndicate or newspaper had sent him. They weren’t aware that his plainly cast features were part of a brilliantly clever disguise, natural as living flesh. They didn’t guess that behind it lay the face of a man whose identity was hidden from all the world — the identity of Secret Agent “X.”

Strange rumors had been built up about this Man of a Thousand Faces. His name had been spoken in awed whispers throughout the underworld. There he was feared as a swift, relentless human scourge who seemed to hear all and know all. Yet the police of many cities had been ordered to investigate his activities, trace him down, trap him. For the law regarded him as a desperate criminal. Only a few on earth knew that the direct opposite was true, that this man of strange destiny and mystery was one of the most daringly ingenious criminal investigators alive. For where crime appeared in its most threateningly hideous form — there, also, Agent “X” made a habit of appearing.

Yet his arrival now seemed oddly inconsistent. Darkness had fallen. Fearful accidents had occurred. People had been trampled, killed. But Nature, not man, seemed the guilty one.

The Secret Agent left the store, strode on down the block, and a figure suddenly stepped from a doorway and accosted him.

“Mr. Martin!”

The man was tall, redheaded. There was on his face a look of strain, as there had been on those others in the store. “Mr. Martin,” he said again. “Listen — the sun’s shining now. But it wasn’t a few minutes ago when I called you. It got dark, black as hell!”

The Secret Agent didn’t answer. There were lights of strange intensity in his eyes. Wild and fantastic had been the description of the people in the store, and the snatches of hysterical conversation in the street. Nightmarish they had seemed. But now the man before him, Jim Hobart, his own operative, whose powers of observation he trusted absolutely, was repeating the same thing. Darkness, as black as night, as black as hell, had fallen. And those fear-stricken people, those dead men and women and children, proved that under its cloak hellish things had happened.

“There was looting,” Hobart continued, “like I told you. I could hear windows smashing and people yelling. What a story it will make, chief! Better hurry before the other sheets get in on it.”

The Secret Agent made an angry, impatient gesture. Hobart hadn’t seen those children, those slain innocents back there. He didn’t know how horribly death had struck in this street of mystery.

“Wait!” he said harshly. “First I must see—” He left the sentence unfinished, gave no indication of what it was he hoped to find. But there was a bank building in the precise center of the block. The Agent hurried on toward this.

Dignified marble columns rose above the pavement. Granite steps led up to the bank’s facade where polished bronzed plates were set. It, too, had apparently come under the dread shadow of the terror fog, the darkness that none could explain. For when the Agent climbed the steps he stiffened abruptly.

The glass in the big front doors was broken, shattered. Behind them there were other signs of ruin. Windows along the tellers’ cages had been smashed. No employee of the bank was in sight. But at the far end of the main corridor, a crowd of depositors stood huddled, men and women who turned their fear-blanched faces at him, like dazed and frightened cattle herded into a pen.

The Agent strode swiftly toward them, and suddenly stopped in shocked amazement, clenching his hands at his sides. For these people had been treated like cattle. Searing welts showed on the features and hands of many. Plainly they were the marks of whips. Whips that had streaked out from behind that cloak of darkness. Whips with metal studded ends that left not merely welts, but jagged crimson cuts. And they had been plied ruthlessly.

A half-fainting girl cowered against a wall desk, her dress torn to ribbons where the sharp lashes had fallen, her white body was a crisscross of angry welts. She had been struck again and again as though some fiend had held the whip. One blow had landed on her cheek, laying it open, making a cruel wound that might disfigure her for life. She could only whimper now, and cower, dabbing a handkerchief to her crimson-stained face. But a man in the trembling terrified group addressed the Agent with hysterical shrillness.

“The police!” he screeched. “Get the police! This bank has been robbed. Those devils who whipped us — while the darkness came — have looted the vaults! They’ve murdered the tellers!”

A noise sounded as he spoke. It was a man’s groaning curse. Agent “X” whirled. A bank employee in a gray coat was getting up, reeling into sight. He had been lashed into helpless, pain-racked terror. And behind him the great door of the main vault was open, papers scattered across its floor, every metal compartment emptied of currency and coin.

A second depositor spoke then, words grating bitterly from between bruised and lacerated lips. “They grabbed my wallet!” he snarled. “The bank’s cash wasn’t enough! They took even the money I’d drawn out.”

Others nodded agreement, complaining that they had been robbed of all they had. Agent “X” stood tensely silent. He was not thinking of the reports of robbery — except that they confirmed his startling suspicion. Man, not nature, had made this hideous darkness!

Mysteriously, abruptly as it had fallen over one whole block in the very heart of the city at high noon, somehow human hands and human brains were responsible for it. A great theft had taken place. Ruthless raiders had gone about their sinister work, unseen, yet able to see.

Those accidents, those stampeding crowds, those pitiful, trampled bodies had been only indirect results. Back of this inhuman carnage — was human greed.

Chapter II

AGENT “X” left the bank quickly before police detectives arrived. They would have their opinions. But there was one whose opinion “X” wanted to hear even more. He returned to the spot where the blind beggar had stood. The sightless man, Thaddeus Penny, was still there, and once again his face lit up as he heard the Secret Agent’s steps.

Months ago, in the disguise of “Robbins,” Agent “X” had done Thaddeus Penny a great service. And Penny had become his friend for life. He had helped “X” often with his power of identifying men by their steps, his trick of never forgetting the tone of a voice, his strangely acute intelligence. He was one man the Agent could come to in any disguise, since it was “X’s” speech which identified him to the blind man, and the Agent was always careful to use the same voice in addressing him. Yet in spite of this “X” sometimes suspected that Penny knew more than he let on, and was aware that the man called “Robbins” was a unique and mysterious being.

The Agent asked an abrupt question, “Tell me just what you heard as you stood here, Thaddeus. Exactly what were the sounds?”

The blind man was silent for a moment. His expressive face showed that he was recalling unpleasant impressions. He spoke slowly, sadly. “There are things a man would rather not hear, Mr. Robbins. People were hurt. They screamed, trampled each other. And I, a blind man, could do nothing. They spoke of darkness. But I am not afraid of the dark. I told them not to be afraid, but they wouldn’t listen.”

“But the bandits?” “X” urged. “Did you hear them come?”

Thaddeus Penny looked puzzled. “I heard them talking. I heard one give orders to the others. But they didn’t sound like crooks, Mr. Robbins. They spoke like gentlemen — men like yourself.”

“I see,” said the Secret Agent. “Thank you, Thaddeus.”

The blind man clutched his arm suddenly, seemed to be looking off into space with his sightless eyes. “There’s one thing, sir, that I almost forgot to tell you. It seems — funny! All around me I heard people shouting that it was dark, pitch dark. And yet — the sun was shining all the time.”

Agent “X” stared at the sightless face. “The sun — but how could you be sure of that, Thaddeus?” he asked sharply. “This is winter. The sunlight is weak.”

“Those who have no eyes must learn to feel many things, Mr. Robbins. I always know if the sun is out or not, no matter how feebly it shines. My skin tells me. And the sun was shining today at noon, while people screamed about darkness. I swear to that.”

Agent “X” was tensely silent. What utter madness was this? The sun shining, while a thousand human beings cried their terror in abysmal darkness, while his own operative Jim Hobart spoke of the fearful night. Was it the product of Thaddeus Penny’s brain — or had a blindman’s delicate senses “seen” what normal eyes could not?

LATER that day Secret Agent “X” crouched over a desk in the small office of “A. J. Martin.” He was alone. Newspapers were spread before him. Black headlines screamed the story of the bank robbery which the metropolitan press had rushed into extras. A dozen theories had been put forward to explain the darkness under which such hideous things had happened.

A smoke screen, vaporizing quickly, some said, had been thrown over the block. Still others claimed that a restricted, radio-induced solar eclipse had occurred. That the thing was man-made all agreed.

But the press and the police were equally baffled. There was no inkling as to the fiendish criminals’ identity — no clues save those bloody welts on the faces and bodies of those who had been close to the scene of the crime.

The accidents, the stampeding, trampling mobs, could be easily explained now. Autos had crashed because their drivers could not see. Crowds had run in panic from Stygian blackness that seemed to presage the end of the world.

The fingers of Secret Agent “X” clawlike in their tenseness, reached forward, took a clipping from a pigeonhole in his desk. It told of a similar phenomenon, the coming of darkness at high noon, which had occurred a week before in a small town upstate. Only a few people had seen it, a hundred or two at most, and because of the quiet of the rural community and the absence of traffic, there had been no accidents or riots.

The big city dailies, when the story reached them, had made light of it, called it the mass phobia of people who had deluded themselves into seeing something which had no existence.

But Agent “X,” ever on the watch for strange occurrences, had saved the item. A profound student of physical science, he had never before heard of such an occurrence. He had been suspicious that it was somehow man-made. And there had even been in his mind the thought that such a veil of darkness would be a perfect cover for a band of criminals to work beneath.

Now, in the light of today’s robbery, Agent “X” understood. The coming of this darkness in the small town had been merely a preliminary test. There had been a bank in the town, and it had not been robbed. But undoubtedly the criminals who had created the darkness had also made a careful study of the situation — to see whether or not a bank could be robbed. The test, having turned out favorably, they had moved their operations to the neighborhood of a bank in a big city where a daring crime would pay.

AGENT “X” tossed the clipping aside. He searched through the newspapers again, reading over the appalling lists of dead and injured that the accidents during the period of darkness on the block had caused. He looked methodically to see if any of the thousand or more witnesses had enlightening data to give. Perhaps strangers had been seen prowling around the section. Perhaps some odd activity had been noted by some one previous to the darkness. But there were no such reports. The criminals had operated with organized efficiency, with complete secrecy.

Then the Agent came upon a brief item which made him instantly alert, though it was tucked away at the bottom of an inside page. It said:

As a news event it was unimportant, vastly overshadowed by the robbery and accidents that had taken place. But to Agent “X” it seemed vital. His alert mind, trained to probe for the hidden seeds of crime, saw in it a possible sinister significance. He wondered instantly if it presaged another hideous robbery such as that which had taken place today. The bank raided during the noon hour just past had been wealthy, but the Guardian was of even more importance, one of the city’s soundest financial institutions, patronized by scores of thrifty workers.

The Agent reached for a telephone on his desk and dialed the number of the Hobart Detective Agency. His own unlimited resources, drawn from a fund subscribed by ten public-spirited men at the outset of his career, had gone into building it up. It was his to command in any way he wished under the guise of A. J. Martin. Often it, and the Bates’ organization, working independently, had been of service to Agent “X,” running down minor leads which left his own time free for the missions that only he could undertake.

Hobart answered quickly, eagerly, recognizing his employer’s voice.

The Agent read the clipping concerning Ellen Dowe over the phone. Then he snapped an order:

“Find her, Jim. Put every man and woman you’ve got on the job. See how she went to and from the bank. Find out who her friends are. Learn where she ate her meals. Get some trace of her!”

There was a brief pause at the other end of the wire. Then Jim Hobart spoke hesitantly: “I thought, boss, you wanted me to comb the crook joints to see if I could pick up any news of that bank gang! I’ve got half the boys out now and—”

“Recall them!” snapped Agent “X.”

Jim Hobart didn’t argue. Often before his boss had moved swiftly, changed his tactics in the twinkling of an eye, working at times on hunches alone. All this Hobart had attributed to “Martin’s” insatiable thirst for news. Now there was an edge in “X’s” voice which demanded quick obedience.

Hobart immediately promised to round up the men and women under him and start the quest for the missing Ellen Dowe.

THE Agent snapped up the receiver and opened a locked compartment in the bottom of his old-fashioned desk. From this he took a black box that was the size of a small valise. He raised the cover, drew out a length of flexible electric cable with a pronged plug at its end. He thrust this into a wall socket, and bent over the open box.

It was one of the most compact radio transmission sets in existence. Its efficiency was proof of the Secret Agent’s ability in the difficult field of radio engineering, for he had built the set himself. Speech or code could be broadcasted from it. The Agent used a small sending key now, reeling off dots and dashes with the touch of an expert wireless telegrapher.

The message he sent out was in a five-letter code known only to one man in the city. This man was Harry Bates, head of the Secret Agent’s second investigating group. Bates had never seen his mysterious employer. He got his instructions by mail, phone or radio. To him, “X” was known only as the “chief.”

At all hours of the day and night Harry Bates kept a small receiving set within hearing, so that when his personal signal was called he might give instant attention. The insect buzz of that secret code generally meant that the chief was beginning one of his startling campaigns to unearth the cryptic details of some hideous crime. And “X” had built and sent by mail to Bates a portable radio set so small that it could be carried inconspicuously on the operative’s person.

When the Agent was sure that the signal code word had been picked up, he gave Bates instructions to send men drifting through the underworld with an ear open for word of the ruthless bank bandits. There was little likelihood that anything would come of it. Criminals clever enough to use such a thing as this curtain of darkness to aid them in their crime would hardly leave traces behind for underworld gossips to talk of. Yet it was a stone that must not be left unturned.

Hours passed, and neither the police nor the Bates organization turned up anything of importance. It wasn’t till the next morning, shortly before noon, that a message reached Agent “X”. It was from the excited, triumphant red-headed Jim Hobart. He said:

“We’ve found her, boss. We’ve got the gal you want, but—” Hobart’s tone became slightly mournful—“she’s been croaked. Hurry, anyway, and you’ll make a scoop on the yarn. Even the cops don’t know about it yet. Dwyer and Lancy Streets, right behind the fence in the vacant lot.”

Agent “X” asked no questions. A strange, harsh light had leaped into his eyes at the news. He got into his car, made rubber burn as he sped through the morning streets. Dwyer and Lancy — that was on the west side of town. Not a nice neighborhood, either.

He saw the red-headed detective lounging on the corner as he turned into Dwyer street. A cigarette hung placidly from Hobart’s lips, but his eyes were snapping. He was proud of the thing his organization had accomplished, proud that he’d been able to fulfil the mission his boss had imposed upon him. The fact that the girl was dead was only a minor disappointment, all in the day’s work. He had seen many corpses in his grimly practical career.

Agent “X” brought his car to a skidding stop, leaped out.

“It was a neat job, if I do say it,” Hobart stated buoyantly. “We found she drove a car, got the tire tracks in her own garage. One of my men located the same tracks in some mud out here. Her own bus was used for the job. Maybe she had a crazy boy friend who did it.”

“Where is she?” asked “X.”

JIM HOBART turned and sauntered into the vacant lot. He moved along the inside of the fence, stopped, and indicated a pile of old boarding that had been shoved away. Under it, a rough hollow had been scooped in the ground, and the body of a girl lay there. Her dress was torn to pieces, like that of the cowering girl he had seen in the bank. On her face, neck and shoulders the cutting marks of the metal-tipped whips showed. Pain and horror were registered on her set face and in her glassy eyes.

“We saw where the car had stopped,” Jim Hobart went on. “Then we found footprints at the edge of the lot and saw somebody had shifted that lumber. Only one guy brought her. He wore number ten shoes. He must have weighed about a hundred and seventy, judging by the depth of the tracks. I knew it was the right gal as soon as I saw her, because one of my boys wangled a picture from a friend. Looks like a crime of passion, boss. Lovers these days—”

But Agent “X” instantly shook his head. The marks of the whip had told him what he wanted to know, confirmed a theory that lay like a black shadow on his mind. This wasn’t the result of a lovers’ quarrel. Cold-blooded purpose had been behind that merciless beating. The Agent turned and snapped quick orders.

“Tell the police about this girl at once, Jim. But say you were employed by a member of her family to find her. And here’s another job for you. Go to my office as fast as you can and get the movie camera you’ll find there in the closet. There’s film in it. You know how to work it. Go to the Guardian Bank where this girl worked. Find a window somewhere across the street overlooking the front entrance. Don’t let anyone see what you’re doing. If the darkness should come again today the way it did yesterday — crank that camera for all you’re worth!”

Jim Hobart’s jaw dropped and he stared in amazement at the man he called Martin — stared as though he thought his chief had suddenly gone crazy.

“You don’t mean, boss — you don’t want me to take pictures in the dark. It wouldn’t do much good. Why—”

The Agent’s answer was low-voiced, grim, with a note in it that Hobart had learned to obey unquestioningly. “You heard me, Jim. Take pictures — no matter how dark it gets. Understand?”

“O. K., boss.”

The Agent turned on his heel, strode to his parked coupé and sped away. He glanced at the clock on the car’s instrument panel. It was twenty minutes of twelve now. Twice the mysterious darkness had descended at high noon; and the second time panic had occurred, grisly accidents had taken place and millions of dollars had been stolen. If what he feared was true, the darkness was about to descend again — and he might be too late to prevent the hideous catastrophe that would surely follow.

Chapter III

YET as Agent “X” raced on his self-imposed mission, he made one swift detour. This was necessary. His disguise of A. J. Martin was valuable. He must run no risk of having it linked with the activities of the mysterious Agent “X.” More important still, it would not serve the purpose he had in mind.

He stopped at a hideout, one of several he maintained, and there made a swift change of disguise. He removed the plainly cast features of A. J. Martin, which formed a carefully molded, flexible covering of plastic material. This had a pyroxyline base, but contained other volatile substances in a compound known only to Agent “X.”

Disguise was the backbone of his strange power, just as it had been of many another great crime hunter, from the incomparable Vidocq on down the line. But Agent “X,” studying the methods of predecessors and contemporaries, had made of disguise an exact science. The skill of a character actor on stage or screen had gone into his work. The art of the sculptor was manifest in the genius with which he caught men’s likenesses.

After the removal of the Martin disguise, including the perfectly fitted sandy-haired toupee, Agent “X” appeared for a moment as he really was. Here was the face that a score of police heads throughout the nation would have given a small fortune to look upon; the face that none, not even his few close intimates, had ever knowingly beheld. For the Agent’s true identity was a jealous secret, guarded with his very life.

The features exposed now in the seclusion of his hideout were as remarkable in some respects as the man himself. Youthful, powerful — they were filled with character and understanding. A forceful, original mentality showed in the clear brilliance of the eyes. Kindness and even a trace of grim humor were combined in the mobile lips. The curve of the nose held hawklike strength. But perhaps the most extraordinary thing of all about his face was its odd changeability. Seen in an oblique light it seemed to grow more mature; planes and hollows were brought out, the indelible marks of a hundred strange adventures and experiences.

Seated before a collapsible, triple-sided mirror, Agent “X” quickly built up a different personality. From a small bottle he washed on darkish pigment that dried almost instantly, owing to its highly rarefied benzine base. Over it he spread a volatile substance that quickly assumed the appearance of ruddy, living flesh. This he molded into the cast of a firm-jawed, stern-looking man of fifty.

He darkened and thickened his eyebrows, slipped a toupee shot with gray over his head — and the transformation was complete. He had aged at least twenty years.

From a small cabinet he took a card bearing the name of Frank Hearndon, agent of the U. S. Department of Justice. This he slipped into his wallet. When it suited his purpose, “X” never hesitated to act as a representative of the law, for, though neither the police nor the D. C. I. suspected it, he had the secret sanction of one of the highest government officials in the land. Messages had often flashed between Agent “X” and a man in Washington, D. C., who preferred to be known only as K9.

The change had taken Agent “X” exactly eight minutes. He slipped into another suit, hurried to the street again. But now he ignored his black coupé, which was registered under the name of Martin. He summoned a taxi instead, and, with a five-dollar bill, bribed the driver to law-breaking speed across town till the Guardian Bank hove into sight.

As he had feared, it was crowded. For this was the first of the month, and at least a hundred depositors jostled at the tellers’ windows, some drawing out cash, others depositing part of their salaries.

“X” strode toward the bank’s rear where a short flight of steps led to a balcony lined with the offices of the officials.

A big man in a blue uniform barred his way by placing a determined hand on the small gate across the steps.

“Sorry, sir,” he said. “We don’t allow—”

“I must see President Banton,” the Agent snapped. “It’s vitally important.”

“Sorry,” repeated the bank guard, “but you’ll have to wait. Mr. Banton is engaged. Take a seat over there. I’ll let you know when you can—”

There was pompous assurance in the guard’s tone, but it vanished in a surprised gasp, as Agent “X” impatiently brushed the man out of his way, snapped open the metal gate, and sprang up the steps.

“Hey — you can’t do that! Mr. Banton is—”

His words fell on unheeding ears. “X” was already half across the balcony. He swiftly passed a dozen doors lettered in gold. The bond department. The trust officers’ rooms. The chambers of the vice-presidents. He yanked open a door marked, “President,” entered a small, luxurious outer office.

An angry voice reached his ears, not Banton’s, but that of a man who stood before the desk of the girl receptionist. “X” paused an instant to stare. A dispute was obviously in progress and the two engaged in it were too excited to notice his entry.

THE man was firm-jawed, powerful, with a face that was familiar to Agent “X”—a face that had the stubborn cragginess of rough-hewn granite. He was Norman Coe, head of the Citizens Banking Committee, an organization representing the claims and complaints of depositors in a dozen closed banks, and a man who had made life unpleasant for more than one shady banker.

“I tell you,” he shouted, “that Craig Banton can’t treat me like this. I’ve waited for twenty minutes now, and I’m going in or—”

The girl at the desk was stubborn also, with the scared determination of one eager to make good on her job. She shook her head. “It can’t be helped. You’ve got to wait — like any one else. Please be patient.”

Norman Coe broke into another angry tirade, pointing a shaking finger at his watch.

“Twenty minutes, I say — twenty minutes. My time is worth—”

Agent “X” took the opportunity to cross the room swiftly. Coe heard him and whirled. The girl at the desk gave a startled shriek, putting her hand to her mouth. But Agent “X” had already flung open the door of the president’s office. It might serve as an adequate barrier even to such an important person as Norman Coe, but it couldn’t stop the Man of a Thousand Faces when the threat of crime spurred him on. He saw at once, however, that the girl at the desk hadn’t lied. Craig Banton was busy — very much so.

A fashionably-dressed woman was seated close to his side — a woman whose face was familiar to the Agent, just as Norman Coe’s had been. While Banton let Coe cool his heels in the outer office, he was having a tete-a-tete with Vivian de Graf, society beauty, whose sensational affairs had formed front-page gossip for the scandal sheets. Only recently her name had been connected with that of Roswell Sully, millionaire utility magnate, called the most hated man in America.

Arresting, exotic, Vivian de Graf was the type to attract men wherever she went. And she made a point of doing so. Her tailored clothes subtly accentuated the perfection of her statuesque figure. Her beauty was carried with poised arrogance. At the front of her gown, contrasting with the dazzling whiteness of her throat, were the spread petals of an orchid, yellow as saffron, spotted like a leopard’s coat. The flower was as exotic as its wearer — and had something poisonous in its loveliness that seemed symbolic of Vivian de Graf’s spotted career.

The caressing smile on her crimson lips, the coyly arched eyebrows, and the confiding closeness of her chair to Banton’s, indicated to “X” that he had broken in on a very intimate conversation.

Craig Banton, red-faced, bull-necked, looking a little foolish at the moment, raised glittering eyeglasses and made an angry sound in his fat throat at “X’s” informal entry.

“How the devil did you get in here?” he barked. “I thought I told—”

Secret Agent “X” strode forward sternly, plucking the card of Frank Hearndon from his wallet and thrusting it under Banton’s nose.

THE bank president’s beefy face got redder still. “Hearndon!” he spluttered. “Hearndon, eh! What in thunder do you want? Why do you come in like this? I don’t understand and—”

Agent “X” spoke a single swift sentence. “I want you to close this bank, Banton.”

At his blunt words, Craig Banton gasped; then gaped, thunderstruck.

“Get every depositor out of here as fast as you can,” the Secret Agent ordered. “Shut and lock the doors. Get the vault closed.”

“You’re mad!” Banton found his voice in a scornful exclamation. “Do you know what you’re saying? I’ve received no orders—”

“Never mind orders!” the Agent snapped. “This bank must be closed — at once! Do you understand?”

Vivian de Graf gave a silvery, rippling laugh. “It’s just too thrilling!” she drawled. “Like a motion picture!”

Watching Agent “X” amusedly, she opened her small handbag. Her slender fingers, conspicuously scarlet-tipped, reached for a cigarette. Stray sunlight from a high window danced and shimmered on a mirror on the inner edge of her bag as she snapped a small lighter into flame, touched it to her cigarette. She leaned back and blew smoke through her nostrils. Still smiling, she said:

“Go on with the show! I came here expecting to be bored with a lot of business details, but all this is vastly entertaining.”

Craig Banton made a gesture of annoyance. He cleared his throat harshly. “This may be amusing to you, Mrs. De Graf,” he said sourly, “but it hardly amuses me!” He stared at the Agent tense with irritation. “I say again you must be mad! What you ask is utterly impossible! Don’t you realize that closing the bank would be taken by the depositors as a sign of weakness, that—”

Agent “X” struck the desk. His eyes snapping, he glared into Banton’s face. “If you don’t get every depositor out of your bank,” he said slowly with, grim emphasis, “if you don’t close up at once without further quibbling, you may regret it to the end of your days!”

Speechless, impressed in spite of himself with the Agent’s words, Craig Banton stared uncertainly at the man who had come in like a human cyclone and made his astounding demand. He started to protest again. But the words died in his throat, and an expression of stark terror replaced the sneer on his face. Slowly, woodenly, he turned his head. And Vivian de Graf dropped her cigarette. The sunlight streaming through the window seemed suddenly to have grown dimmer.

Agent “X” felt a sudden, faint sense of giddiness. A humming sound buzzed in his head. Pinpoints of colored light danced abruptly before his eyes. Then they stopped — and he saw that dimness was filling the office as though twilight were swiftly falling.

Craig Banton spoke thickly, harshly, clutching the edge of his desk with shaking hands. “Good God! It — it’s getting dark!”

Vivian de Graf, close beside “X”, gave a small, stifled shriek. Her aplomb, her smiling amusement, had vanished. Agent “X” took one step toward the window and stopped. He could hardly see at all now. Uncanny, awe-inspiring darkness was descending like swift night, blotting out the sunlight, making the luxurious office of Craig Banton a sightless cavern.

And Agent “X” knew what it meant. He had come too late. The ruthless devils of darkness had arrived.

Chapter IV

A SMOTHERED exclamation burst from his lips. He had been prepared — but the stunning actuality of the thing was beyond all reason. The silhouette of the window had faded before his eyes. The last vestige of light had disappeared from the street outside. The glare of the sun, high overhead, shooting its bright beams straight down, had vanished as though a total eclipse had taken place.

Blood pounded in the Agent’s temples. His throat felt constricted. He whipped a small flash from his pocket, clicked it on. He couldn’t see it at all. He brought it to within an inch of his eyes. For an instant a faint, cherry-red glow was visible. Then that diminished, too — like a coal dying out. The terrible blackness was complete!

There was noise, mad confusion in the big bank. Girls screamed. Men were shouting. Agent “X” could hear the clatter of running feet. There would be another stampede, bringing horrible death in its wake, as when the first bank was robbed. He turned, groped his way toward the door of Banton’s office, flung it open. At the top of his voice he shouted a warning:

“Quiet — everybody, quiet! Don’t run — and you’ll be safer!”

Some few heeded. There was a momentary lull. The Agent shouted again, hoping to avert the horror that panic would cause. But even in that he was too late. Glass snapped and crashed in one of the big doors, giving way before the thrust of wedged, frantic humans. Then came a louder crash. A scream, piercing in its intensity, sounded from Banton’s own office.

“X” whirled, turned back and stumbled through the door. That scream had come from the lips of Vivian de Graf. The crash he could not identify at first. Then, as the odor of gasoline and hot oil reached his nostrils, he realized that some vehicle had crashed into the side of the bank, smashing the window of Banton’s office.

Vivian de Graf screamed hysterically. Obviously she was unhurt, but the sound of the accident had unnerved her.

“Better stay where you are,” said “X” harshly. “You’ll be safer — all of you.”

He couldn’t see, any more than they could. For once the Man of a Thousand Faces was helpless. But his nerve had not been shaken. He felt no fear — only dread of the horror that might lash out at the innocent people caught beneath this curtain of dark.

The sounds from the main floor outside had risen into a frenzied uproar. Men and women, crazed by fear, were shrieking, stampeding. Aghast at the possibilities of death and destruction in that mad bedlam, “X” started toward the door again, to make another desperate attempt to recall the mob to sanity.

But on the threshold he froze, listening. The milling of frenzied feet had abruptly stopped. The cries that rent the air had taken on an added shrillness. They rose in a piercing crescendo of sheer terror. Coldness clutched the Agent’s heart. For above the horrible confusion he detected another sound. The spiteful, vicious cracking of whips.

Like miniature gunfire the crackling of metal-tipped lashes echoed through the bank. In its wake came stark cries of pain, like those of wounded animals. The blackness, fearful enough in itself, had become a living, lurid hell.

In Banton’s office there was no sound now beyond the echo of horror and the scrape of hoarse breathing. All stood frozen, listening to the blood-curdling drama being enacted outside.

Driven by pain and fear, a man in the depositor’s corridor broke into a tirade of frenzied curses. The answer to that was a whip crack like a tongue of vicious lightning singling out a place to strike. The man’s curses rose to maniacal pitch, then diminished beneath a salvo of crackling torture, to die away in a whimpering, long-drawn moan.

Little by little the snapping of the whips died away. Agent “X,” in total darkness, could vision graphically what was taking place. He could see the depositors, their clothing torn, arms and faces lashed into bloody streaks of torment, cowering back, falling over each other to escape the metal-tipped whips. He pictured the raiders’ slow, methodical advance, as they plied their lashes till the floor was clear.

But how could they see, when the darkness was more complete than any night? Agent “X” was as baffled as he was appalled by the course of a crime more astounding than any he had ever known.

THE whip cracking was hardly audible at all now. That meant that the crowd of scourged men and women were huddled like dumb beasts in pain-racked passivity. It meant that the raiders had achieved their purpose — cleared the way for robbery.

A moment passed. Then came the faint clank and clatter of metal boxes. Compartments in the great vault were being opened and dumped out. Then, as Agent “X” stood desperate and helpless in the impenetrable darkness, his ear detected footsteps approaching Banton’s office. Ghostly and measured, they moved across the outer room. The girl at the reception desk gave one terrified cry. Her chair clattered as it overturned. The steps passed her, entered Banton’s inner sanctum.

Agent “X” stood frozen like the others. Not with fear, but with sheer amazement at the thing. It was uncanny, beyond belief, that any eyes could penetrate this darkness which seemed almost to have a substance of its own. But a voice spoke to them — low, harshly evil.

“Keep your seats — all of you. You who are standing, sit down!”

Agent “X” did not move.

The voice challenged him harshly, proving beyond doubt that the newcomer could see. “Sit down!”

Agent “X” stepped back slowly, found an empty chair and sank into it. His eyeballs ached, as he strained his eyes toward the spot whence the voice came — the voice of a man whom he could not see but who, somehow, was able to see him. A harsh chuckle sounded.

“It is fortunate, Banton, that the vault was open. Otherwise we would have had to blow it up — which would have been inconvenient for us and troublesome for you. As it is, everything is going nicely. We shall soon be away from here.”

The laugh was repeated. Then silence followed. Slowly the steps moved away. The faint noise of the raiders methodically at work filled the black hole of silence in the room.

A moment later Agent “X” lifted his head alertly. There had been an infinitesimal stir in the air. He had felt it — and his nostrils caught a faint whiff of perfume. The scent was exotic, cloyingly sweet. He crouched forward in his chair, every nerve taut. And in the silence he caught the sound of whispering. A very guarded whispering, as though two people were in secret conference, and anxious not to be overheard.

Who was it? Who in the room had moved?

Pulses racing, “X” slid cautiously from his chair. Though he could not see, his mind retained a photographic picture of the arrangement of the office. He knew where Banton’s desk was, where Banton sat, and where Vivian de Graf had been.

His fingers reached oat, groped lightly. He took a few steps forward. Banton was sitting in his chair, rigid. Then the Agent stepped to the right — and grew tense, for the chair where Vivian de Graf had reclined languidly was empty!

Either she had left in fright, to huddle in some other part of the room. Or it had been she who—

The Agent was given no time for speculation. A curse, sounding in the darkness at his left, cut it short. “X” could not see anyone approach, but his acutely alert senses warned him that the man who had cursed was striding in his direction. Instinctively he raised his arms over his face.

As he did so there was a hiss and a snap — and the serpentlike end of a whip snarled about his arm. Its metal-tipped end, fanglike, bit into the flesh of his wrist. He wrenched his body sidewise and pulled his arm clear. The whip came back at him. It struck his neck this time, coiled about it like a loathsome snake. A scalding brand, the metal tip licked up at his cheek.

AGENT “X” did not cower away. Taunt as steel, eyes blazing in the dark, he reached out and grabbed the leather lash. He pulled it toward him and plunged straight at the unseen figure wielding it.

The man with the whip gave a startled, angry cry. Furiously he tried to wrench free. Again the whip was a snake, coiling frenziedly in the Agent’s grasp to free itself, to strike at him again. But his hands moved tenaciously along its pliant length until they encountered human fingers.

His own hand closed over the whipman’s arm. He swung savagely with his clenched left fist. But he could not see. The other could, and eluded the blow, struck back. “X” closed with his unseen adversary, driving home body blows, and they fell to the floor together in a fighting, clawing heap.

He was conscious again of a scream from Vivian de Graf. He felt the breathing of the man he fought. His opponent had dropped the whip now, was trying to break loose from the Agent’s hold. But “X’s” hands, vicelike, did not yield.

This was no darkness he was fighting now. No whip that struck treacherously from behind a curtain his eyes could not penetrate. This was a living, vicious man — one of the raiding gang. And “X” fought with the bitter anger of one who remembered the pain-racked screams of those innocents outside. He fought with punishing blows, craft and science disregarded for the moment in the primitive joy of meting out justice to one who had caused the torment of others.

Then his right hand, lifting for an instant to clutch at the other’s throat, tensed uncertainly. He had felt something — a mask or hood made of a substance that felt like pliant rubber. It covered the man’s shoulders and head. And across his face were heavy goggles. In a flash Agent “X” had the answer, incomprehensible as yet, as to how the raiders saw their way about in the darkness. Somehow they had protected themselves against the night they created.

With fierce eagerness “X” sought to tear that hood from the man’s head. He was sure that without the hood his opponent would be as helpless as he himself.

But the other apparently sensed his purpose, and began fighting like a living fury. Lifting a knee, he gave a savage, treacherous blow, twisted and turned on the carpet. Agent “X” thrust his knuckles against the man’s heart in a jiu-jitsu blow, which, if he had not been handicapped by his cramped position, would have ended the fight then. As it was, it struck with only half strength, and his own movements weakened. Air whistled from between his teeth.

Then, through the thunder of his own pulses, “X” heard the clatter of feet on the tiled corridor outside. He strove desperately to deliver another blow. He must knock this man out, take off his hood before help came. If the hood enabled him to see, he might be able to do something. The labored breathing of his opponent told him that victory was almost within his grasp.

But at that moment a new voice snarled an oath, and before the Agent could leap away in answer to the warning of his senses, something struck him heavily beside his ear. Something that made lights dance before his eyes, and seemed to bring the black room crashing down about his head. He stiffened, gave a choked gasp, and collapsed senseless over the man he had almost mastered.

Chapter V

A SWAYING vibration accompanied the slow struggle of the Agent’s senses back out of the black pit into which they had been plunged. The dark in his brain, coming on the heels of that other dark in Banton’s office, had left a blank page in his memory. He was dazed, uncertain.

Then, without conscious effort, his will fought to regain its poise, aided by the balanced nerves of a perfectly coordinated body.

The swaying which seemed part of some hideous nightmare became gradually familiar. His ears picked up sounds that registered in his brain. He was in an auto, traveling swiftly. The swish he heard was the sound of tires. That rumble was the throaty voice of a heavy engine. He was in an auto, and these criminals who worked behind the black fog were taking him away, bound hand and foot.

“X” discovered then that he still was unable to see. But it was not the unearthly darkness this time — only a prosaic strip of adhesive taped across his eyes that shut out the light. He knew, of course, why he had been made a prisoner instead of being killed on the spot. Some one had found out that he had warned Banton of the raid. And his attack on the man with the whip, his refusal to be cowed by fear like the others, had frightened the raiders. They thought he must know something about their activities, and they wanted to find out exactly what.

Twisted and cramped on the car’s floorboards, an old wound in the Agent’s side, made long ago by bursting shrapnel in a field in France, gave him a twinge of pain. Eminent doctors had told him at the time that the wound must kill him. Yet he had gone on living, his magnificent vitality triumphant. The pain from that wound invariably acted as a spur to a steely grimness of intent. And, curiously enough, the cicatrix of the wound took the form of a crude “X”—a living, pulsing symbol of the Secret Agent’s indomitable spirit.

His fingers curled tensely, reached back and touched the ropes binding his wrists. Given time he could get those bonds off. But there was no time for that. The auto was slowing already. The rumble of the motor diminished and the vehicle turned lurchingly with a grate of shifting gears. It entered some sort of drive or alley, and stopped. Garage doors rumbled back, the car plunged forward a few feet, came to a standstill. The doors clanged shut.

Voices sounded, clipped and indistinct. A second of silence, then rough hands abruptly reached in and yanked the Agent out. He made no attempt at struggle. Feigning complete unconsciousness, he let his body sag.

Every sense was active, every nerve alert as they carried him into a building and down a flight of steps. A short, straight passage was traversed, a door was opened, and warmer air told him that they had entered an inside room. His captors dropped him to the floor as though he had been a sack of grain.

He lay inertly while other doors slammed and feet moved by. Then voices sounded behind an adjacent wall. He strained his ears, but even to his acute senses the words were unintelligible. If only he had his hands free, and could use some of the strange devices he carried. Pressing his elbows experimentally against his sides, he could tell that these things, worn in secret pockets inside the linings of his garments, were still intact.

Swiftly, surely, his finger ends touched and tested the knots that bound him. But before he could loosen even one, a door opened close at hand. A heavy tread crossed the floor toward him. “X” lay still, not knowing who it was that stood above him. It might be some grim murderer commissioned to blot out his life with knife or bullet. But “X” was gambling on the premise that he wouldn’t have been brought here unless his captors wanted him alive.

Not by a single quiver did he betray himself. He was as one plunged in an abyss of sleep. The man moved to the wall of the room, returned, and flung a bucketful of icy water into “X’s” face. The Agent did not stir.

An outthrust toe followed the water. It prodded, then delivered a brutal kick. Dizzying pain almost drove the breath from his body. But the groan that escaped his lips was calculated; the groan, apparently, of a man whose senses were still lost in a daze.

A voice above him sounded, barking a sharp order.

Shuffling footsteps responded, those of at least three men. They entered the room, walked to “X’s” side. He was jerked roughly to his feet and flung into a chair.

“Wake up! Wake up!” He was shaken roughly.

This time the Agent didn’t even groan. He let his head hang forward, lolled and slumped in the chair.

“Maybe he’s finished,” a cold voice said. “That bruise behind his ear—”

THE man who seemed to be in charge spoke again. The Agent recognized the voice as the one he had heard in Craig Barton’s office.

“Don’t be a fool. Untie his wrists. Work his arms and get him breathing. And look out for tricks. You, Fritz, shoot him in the leg if he tries anything. We don’t care if he’s crippled.”

There was utter callousness in the tone. Yet neither this voice nor those of others, were the voices of underworld criminals. No slang was here, no thickness of accent. It was the smooth, precise speech of educated men.

The Agent’s arms were freed and moved forcibly from side to side as though he were drowning. He could feel blood coursing through his veins, prickling in the stiffened flesh of his wrists. Keeping up his part, he groaned again. The working of his arms continued. Slowly he let his body stiffen, closed his mouth which had been hanging slackly open.

Something struck against his face with a ringing smack that nearly made him jump. Crack, crack! It was the leader, slapping him with flattened palm. Fury surged over the Agent, but he forced it back with iron will. The blows stung painfully, even through his flexible disguise.

He stiffened a little more, feigning the behavior of a man returning slowly to consciousness. The man who had slapped him laughed harshly. “Wait,” he said, “here’s something else. That ought to fix him.”

A pain like a knife thrust curled the nerves of “X’s” wrist, as a cigarette’s lighted end was pressed into his flesh. But the Agent had schooled himself to stand pain. Spartan courage had saved him in more than one perilous situation. Torture had been his lot before. He opened his mouth, emitting a sudden hoarse cry, exactly as a man resuming consciousness might be expected to do. He lashed out wildly with one arm, mumbling incoherently.

He was instantly pinioned on either side. The grim voice of his torturer spoke in front of him.

“So — you’re back with us again, Hearndon!”

Agent “X” let his mouth gape with mock surprise.

“Yes,” the other sneered, “we found your card. We brought you with us just for a friendly little visit. We think we’re going to find your conversation most entertaining.”

Agent “X” stiffened, lifted his head toward the speaker. The adhesive tape still covered his eyes and no move was made to tear it off.

“You’re going to talk, Hearndon,” the other continued. “Talk is cheap, and won’t cost you anything. But remember that silence comes dear! Now — what were you doing in the bank? Why did you give Banton a tip? And who sent you to meddle?”

The Agent kept silent a moment, marshaling his thoughts. There was some inconsistency here. They had found his car, addressed him as Hearndon — and yet wondered why he had warned Banton. Did they doubt his disguise as a Department of Justice man? He tried a quick rejoinder in his chosen role.

“You can’t do this! You can’t buck the government. We found the girl you murdered, Ellen Dowe. Not so smart — leaving her there! It wasn’t hard to figure out why she’d been tortured. You birds are washed up now. You’re in a tight spot!”

A harshly sneering laugh was his answer. Then the unseen questioner spoke again, gloating evil in his tone. “A good line, Hearndon! A nice bluff you’re putting up! But drop it now! Talk straight. You’re no D. J. man. You’ve been checked on that. You got away with it at the bank, but not with us. You’re a fake. But I want to know who sent you, and what’s behind it. Understand?”

A COLDNESS stole over Agent “X.” These men were clever as well as ruthless — super clever, keeping track of the Department of Justice lists, guessing so soon that he was a fraud. Had they penetrated his disguise, too? But no, the speech of his questioner had shown they had not done that.

He growled a sullen curse, squared his shoulders, thrust out his jaw. Let them think, if they wanted to, that he was a hard-headed dick from some private agency, posing as a government man.

“All right, Hearndon,” said the mocking voice. “You found the girl we murdered, you say. Ellen Dowe. But you aren’t a dick. You didn’t bring any cops to the bank with you. How was that?”

Agent “X” remained stubbornly silent. A note of icy anger crept into the other’s voice. He thrust his head so close that “X” could feel the man’s warm breath against his face.

“You’ll talk, damn you! We’ll have no snoopers getting in the way. You were at the bank. You heard those cattle screaming under our whips. You found Ellen Dowe — and know what happened to her. Well! Now you’re going to talk.”

The man paused abruptly in the midst of his furious shouting, and when he resumed his threatening of Agent “X” his voice was an insinuating purr, more deadly than the bellowing rage that had preceded it.

“You were a kid once, weren’t you, Hearndon? Maybe your parents whipped you sometimes, too. But not the way we do it. Oh, no! Not with our kind of whips. No man can stay silent under the lashing we give them. Ellen Dowe couldn’t. She told us all we wanted to know. We whipped the truth out of her. Unfortunately our man got over-enthusiastic. Maybe he liked the way she screamed! When I talked to her she was all through screaming. She couldn’t even stand. I promised not to whip her any more if she talked — and she did. It wasn’t our fault if she decided to talk — too late! So you see, it may be too late for you — if you don’t talk now!”

Secret Agent “X” maintained his stubborn silence. He knew, too, that nothing he could say would appease them. Unless he told the truth. And that would mean death — the end of his campaign. They wouldn’t let the Secret Agent go. Even by men like these he would be feared. And what men fear, they kill.

“All right — you asked for it! Let’s see if you can stand as much as Ellen Dowe!”

Two men sprang forward and jerked “X” from his chair. His feet were still tightly bound. No move was made to untie them. They dragged him by the arms across the floor and spread-eagled him on a narrow cot. The two men pulled his arms in opposite directions, almost yanking the bones from their sockets. A cold something was pressed against his scalp by a man at the head of the cot.

“The same way we handled Ellen Dowe,” the cold voice said mockingly. “Except for the gun. You ought to be flattered, Hearndon. I’ve given instructions to shoot you through the brain if the whipping makes you too violent. Now, boys — go to it! Let’s see you tear his coat to pieces!”

The snaky head of the whip was like miniature lightning in the air. The metal tip struck with a vicious crack. Its nipping bite, directly between “X’s” shoulders, proved that the whipman was an expert — as sure of his aim as those professional performers who can snap a cigarette from between human lips on the stage.

Crack! The whip landed again, and the cloth beneath it ripped. In a moment it would be gnawing at the Agent’s quivering flesh. They could not make him talk — but slow, torturing death faced him on that cot.

Chapter VI

NEVER had Agent “X” been closer to complete disaster. Never had the hand of Fate seemed so set against him as now. With his ankles tightly bound he would be helpless as a cripple, even if he could break away. Before he could hop ten paces, he would be shot.

The third blow of the whip sank through his coat and undershirt, breaking the flesh of his back over a bulging muscle. Clothing, skin and living tissue would be churned to a bloody, pain-racked froth if this continued. He did not doubt his ability to steel himself against the torment. But in this case, resistance would accomplish nothing.

As the fourth stroke fell, he let a groan burst from his lips. His body twisted, then sagged. “Stop — stop! Oh, God — I can’t—”

His acting was superb, the whimpering complaint of a wretched, weak-willed man whose spirit had broken. Insensibly the two clutching his arms relaxed their hold. And in that instant the Agent’s muscles, unmarred as yet by the scourging whip, contracted like released springs.

He flung his head sidewise. His right arm wrenched free, tumbling the man who held it off his feet. The arm swept outward, forward, clamped over the wrist of the man holding the gun. The Agent twisted, squeezed until bone grated on bone.

But as Agent “X” struggled to seize the gun, the guard’s finger contracted, and a bullet passed screamingly close to “X’s” chest. He wrenched his left arm free at the same instant, made a furious lunge, and tore the weapon from the other’s fingers.

Swearing, cursing men flung themselves on top of “X” to pin him down, but he struck right and left with the gun muzzle, then gave a savage roll that took him clear of the cot.

Death hovered to the room. The odds were all against Agent “X.” He had the gun — but the tape was still across his eyes; the ropes bound his feet. Apparently his maneuver had been the reckless, futile stunt of a fear-crazed and desperate man. Actually it was based on calculation, logic and a carefully thought-out plan.

For with one swift sweep “X” tore the adhesive from his eyes. Then he held his breath, crouched tensely. The tape was gone — but its cruel pressure on his eyeballs over a period of time had made the retinas cast blurred and distorted images. He could see only that these men in the room with him were masked with some sort of black stuff that made them look now like ghoulish monsters. They were staring at him, coming toward him, and one seemed to be raising a gun.

The Agent fired a single shot quickly and heard a man cry out. He didn’t often kill, but the memory of those crushed and mangled children in the zone of that first horrible robbery was still in his mind. The memory also of the lacerated body of the murdered Ellen Dowe. These men were fiends, human vultures, and what stayed his hand now was not mercy for their lives, but the knowledge that he could not shoot straight because of the state of his eyes — and a pressing need he had for at least one of the bullets in the gun. He snarled a fierce order.

“Back there — all of you! Against the wall!”

They did not know that he could barely see them. His one lucky shot had made its impression. Tensely the masked men moved backward toward the wall.

And, as they stood there, the Secret Agent suddenly did a strange thing. His gun left the masked figures. He bent like lightning, thrust its muzzle between his shoes, felt quickly with the fingers of his left hand, and then slammed a bullet through the ropes that held his ankle. The crashing lead, fired at close range, was quicker, more effective than any knife. Two ropes parted, and Agent “X” spread his feet and kicked the others off.

But his act, quick as it had been, had given his masked enemies a chance for a treacherous move. An arm flashed out, a finger jabbed forward, and there was a click in the room as every light went out. Some one had pressed a switch.

And the instant darkness fell the Agent heard stealthy movement. These men knew the room, he did not, and death was creeping upon him out of the dark. Instinct made him drop, fling himself sidewise, and as he did so pinpoints of flame stabbed the darkness, and a half dozen bullets crashed into the wall, close to where he had stood.

He raised the weapon in his own hands, fired twice and leaped away again. Another cry sounded. His aim at the points of fire had been true. But the next time he shot his gun clicked empty. He was unarmed in that room with killers creeping upon him.

HANDS stretched along the wall, the Agent felt for some possible means of escape. And suddenly the smooth knob of a door brushed against his fingers. The Agent yanked the door open, saw a glimmer of light. He didn’t know, but perhaps this led to the passage to the street through which he had been carried. Then the next second he saw a narrow stairway.

But he had no choice now. He leaped toward the cavernlike mouth of the stairs, dropping to his knees as bullets whined about him. He flung the empty gun over his shoulder, heard it crash into the room, and ascending the stairs in long-legged strides, entered a dark hall. His flashlight, winked on for a moment, disclosed an old-fashioned hatrack, a pair of high front doors with curved Gothic tops. He turned the other way and saw draperies and barred windows beyond. Dusty, ancient furniture stood against the walls. The bandits had chosen an old house, obviously long closed and locked, for their hideout.

He knew there was no quick exit from this floor; knew also that his gas gun, strapped in a flat holster to his leg would not stop a crowd of armed men. As feet pounded up from below, “X” leaped to the stairs behind him, leading to the rooms above. He whipped out his gas gun, expecting to be challenged by more of the band upstairs.

But no challenge came. The rooms on the second floor were empty, their windows barred and shuttered. He knew this type of house. Sixty or seventy-five years old, it was a relic of the brownstone era. There should be an attic, with a wooden scuttle giving on the roof. He climbed quickly, leaped up a short, steep flight of stairs and found himself in the attic. Then he paused.

Sudden silence had descended on the house. No sound of footsteps was audible now. The whole place was as quiet as though the gang of torturers had vanished. “X” considered this unexpected development uneasily. Then, as he peered down over the railing of the stairs, he found a gruesome explanation. A faint draft of musty air came up. And it was tinged with something beside the odor of old walls and dusty furniture. Smoke, acridly pungent, drifted to his nostrils!

He leaned far over the deep stairwell and stared down. At the bottom, four stories below, there was a flickering gleam. Fire! As he watched, it fanned out, turning from red to orange, then to hot yellow flame. Mixed with the smoke funneling up was the scent of gasoline!

The Secret Agent’s jaws clamped shut. He knew the first floor of the building would already be an impassable inferno. He could not go down. The attic had two rooms separated by a short hall. In this a wide-stepped ladder rose toward the roof. He climbed quickly, searched with tense fingers for the hooks in the wooden scuttle.

But he grew suddenly rigid, and felt a coldness at his heart. Not hooks, but huge padlocks held the scuttle down. Two of them, products of some locksmith of long ago, with thick rings stuck through strong hasps bolted to the beams.

It was an obstacle he hadn’t anticipated. He carried tools — the gleaming chromium rods with slender ends and tiny pivotal extensions that had often been used to unravel the mysteries of modern locks. With these no door was barred to him. But these rusty, ancient padlocks — would he be able to open them in time?

Chapter VII

THE sound of the fire was mounting every instant into a fearful, smothered roar. The attic was insufferably hot. Sweat trickled down the Agent’s neck and bathed his body.

The mechanism inside the old lock seemed rusted in a solid mass upon which his delicate tools made no impression. He tried another and another length of metal. He needed oil to free the rust-corroded pivots.

Desperately he thrust his hand into his pocket and brought out a small cigarette lighter. It was of silver, with pebbled leather sides, and had been a present from Betty Dale — the only girl in the world who knew the nature of his dangerous work. With feverish concentration, making every motion of his deft fingers count, “X” drew the woolen wick from the lighter, squeezed drops of the fluid into the old lock. Before taking up his tools again, he treated the second lock in the same way.

Then he adjusted his rod with pivotal extensions, one of his most ingenious chromium pieces. In response to its probing, he felt something give inside the old lock. One piece of metal moved, another.

Somewhere below, a falling balustrade blasted up heat and sparks. Clouds of soot swirled about “X’s” head. The air was scorching. His eyes smarted painfully as he worked.

Slowly the rusted lock worked free. Pivots that had not moved for years creaked protestingly as he got the hang of the pins and slots inside. He found a spot that gave, pressed at an angle — and the curved hasp of the padlock opened.

He drew it out of the staple, dropped it to the floor, and began on the second lock. This should be easier, now that he knew its secret.

But his race with death was getting close. A tongue of flame licked up the attic stairs. Far below in the fiery maw of the old building there was a thundering, like the rumble of an earthquake. The ladder squeaked under his feet as the floor beneath it slanted. In another few seconds he would drop into that inferno of raging flames.

Hardly able to see because of the smoke pouring into the room, “X” opened the second lock. He flung it from him like some poisonous thing, climbed a step higher and heaved up on the scuttle above. Paint broke loose, the scuttle rose, seemed to lift out of his hands as heat exploded it outward. The fire below gave a deep-throated, warning roar. Imprisoned heat shot skyward. Sparks and burning embers whirled past Agent “X” as he sprang onto the roof.

He could feel the tar covered roofing sag under him where supports had given way. It was blistering hot, the tar boiling up in black, sticky, smoking masses.

He leaped to the top of an adjacent house. As he did so the roof over which he had come sagged crazily, one corner fell in with a rumbling crash, and flames volcanoed upward.

The Agent was safe, safe from the death his captors had planned. For he sensed their double motive in firing the house. They wanted to destroy all clues; and they wanted his life as well.

He ran across two adjoining rooftops, found a fire escape snaking down an empty building, and made his way along it to a back yard. The street was cluttered with the hurtling red forms of fire engines. The air was lurid with the wail of sirens and the shrill clang of bells.

But Agent “X” did not linger. He knew the bandits might have a watcher posted. And he wanted them to believe he had been consumed in the flames as they had planned. Let them think Hearndon was gone forever.

In a taxi, he hurried to one of his hideouts. Here he changed his disguise to that of Martin, replaced his sooty clothing with a fresh gray suit, and went directly to the raided bank.

Traffic was moving through the streets again, but there was a police line around the bank itself. Throngs surged about it, jostled and kept back by police. The Agent’s eyes darted on all sides. He saw many excited newspaper men, men from the newsreel syndicates and press photographers, then his gaze wandered to a building opposite the bank.

THERE were small shops along the street floor of this, apartments above. Behind a “vacant” sign in one of the apartment windows Agent “X” glimpsed a familiar face. Instantly he crossed the street and entered the building. Tenants stood in the open door. He brushed by them unnoticed, climbed the stairs.

In an empty third-floor front apartment Jim Hobart was waiting, his movie camera with him. He had used a set of skeleton keys with which “X” had long ago provided him, and had come here before the falling of the fearful dark. But he shook his head when he saw the man he knew as Martin. His face was pale, his voice husky.

“I did what you said, boss — cranked away. But it got dark, so dark I couldn’t see my own hand. And I’m afraid—”

“Let’s have the films.” There was tense excitement in the Agent’s tone. He took the metal drum of celluloid that Jim Hobart handed him, thrust it under his coat, said: “Take care of the camera, Jim,” and was off.

He slipped through the excited crowd around the bank, went to his coupé again. In fifteen minutes he was closeted in a dark room in one of his hideouts. There was elaborate equipment before him. Reels for winding movie film. Trays of chemicals, developer, fixative. The precious drum that Hobart had given him was being slowly unwound, run through its acid baths, for “X” in this small compact chamber could turn out work as finished as that of the laboratories of any movie studio.

For nearly three hours he worked. Then he took, from the reel of a special dryer, a printed, transposed celluloid of the film Hobart had made. He went to a larger room outside the dark chamber, removed a small movie projector from a box and put the film in it. A six-foot screen was on the opposite wall. With tense fingers, knowing already that Hobart’s film, taken in utter darkness had picture impressions on it, he focused his projector on the screen and switched on the electric motor that turned it.

Then the Agent leaned forward in enthralled interest. For Hobart had begun to crank his camera just as the darkness had started to descend. And there on the silver screen before “X’s” fascinated eyes, tiny, weirdly helmeted figures were visible. He stopped the projector once to look at a shot which plainly showed a helmeted head.

Mad crowds of terrified people showed in the street. “X” saw the black car that the raiders came in, saw something else that made his eyes widen. This was a small electric truck that looked like one from the city’s lighting company, and which had parked along the curb not far from the bank. The tiny line of a black cable led from the truck’s end to an open manhole. Then, as the amazing scenes of the raid unwound on the screen, “X” saw the bandits’ black car drive off, after small helmeted figures had carried sacks of loot to it.

More interesting still, he saw the figures of two men in workman’s clothes descend unhurriedly into the manhole; remove the black cable and coil it into the truck. While the whole block was held in icy terror, while a sinister raid was in progress, these men, tapping the city’s electric current, could work calmly. There was only one explanation of that. They were part of the raiding gang, and that light truck housed the strange mechanism which had made the darkness.

But what of the darkness itself? Here on the screen was proof of Thaddeus Penny’s amazing statement, proof that the sun had been shining, did shine, while that darkness fell. The movie camera’s lens had not been hampered by it. The sensitive film, impressionable to light, had functioned normally. Only human eyes had been affected, blinded. Only they could not see. And Agent “X” had uncovered a riddle that seemed too deep to explain.

Chapter VIII

HOURS later, Agent “X” was moving stealthily across the velvet smoothness of a wide lawn. Ahead of him loomed an ornate, old-fashioned mansion set amid thick clumps of shrubbery and tall, leafless trees. Behind him was the high brick wall which he had scaled a moment before.

It was night, starless and black. He was on the property of Roswell Sully, famous utilities man and admirer of Vivian de Graf. For over an hour he had followed her, and she had finally led him here.

There was grim purpose in the Agent’s eyes. Even this clever, provocative woman could not escape justice if she were in league with the criminals. Innocent Ellen Dowe had met an unthinkable fate. Pain had stolen her young life away by inches as she lay helpless and writhing under the sadistic lash of a human fiend. Her death and the deaths of those children must be avenged.

Agent “X,” in his daring battles against crime, had met other women, as beautiful as Vivian de Graf, whose charm had been only a cloak for untold evil; women who used their wit and beauty as bait to gain some unholy end. Vivian might be such a woman. He didn’t know, but he was going to find out. And besides his own direct suspicion, based on the episode in the bank, there were certain facts against her.

She was the wife of brilliant Emil de Graf, professor of science at the university. But she preferred the company of other men. For years Roswell Sully had danced attendance upon her. Unescorted by her husband, she had often been a guest at the unwholesomely gay parties for which Sully was notorious. Her wit and beauty had made her a sought-after favorite with the set of careless ne’er-do-wells who were Sully’s intimates.

Then, with the stock crash of ’29, Sully’s utilities empire had collapsed in chaos, dragging thousands of investors down with it. And Vivian de Graf had aided the former wizard of high finance in the secluded life forced upon him by the debacle. She had acted for him as go-between in financial matters — and “X” knew for a fact that she received handsome commissions on every deal he managed to put through with her help.

Possibly some business of Sully’s explained her presence at the Guardian Bank at the moment when it was raided. Possibly Sully was responsible for the presence of Norman Coe, too. For Coe had helped expose Sully after the big crash, and had worked tirelessly to have him prosecuted for the ruin he had caused. These things the Agent knew. But the woman herself was still an enigma — an exotic, mysterious personality.

The car she had come in, a luxurious phaeton, was parked outside the gates. Sully would allow no vehicle within his grounds. The old carriage entrance was kept closed and locked. Rain or shine, visitors were forced to walk up the long drive. Coal and provisions came the same way. Frequent harsh threats made against Roswell Sully by the investors he had mulcted had made him wary. His past haunted him always like a grim specter, even though he had salvaged enough for himself to live on in luxury. He had been called the most hated man in America.

Agent “X” climbed the wall and dropped silently into the forbidden grounds. With the bleak winter wind stirring the branches of the trees overhead, he crept forward. His senses were alert. It was rumored that Sully kept guards.

“X” was disguised as a young, nattily dressed man; not Martin, but another personality for which he had chosen the cognomen of “Sid Granville.” Under one arm he carried a newspaperman’s camera with focal plane shutter and high-speed lens. If caught, he was prepared to play his bluff to the limit. Vivian de Graf must not be made suspicious — and she would only be amused at the predicament of a young reporter, eager for a scoop. He would admit that he had followed her in the hope of getting a good news story, and a flashlight picture for his sheet. The news value of her presence at the raided bank would be his excuse.

But suddenly the Agent paused and listened. He had heard an ominous sound in the darkness ahead — a dog’s soft growl. He tensed, standing close to the fragrant blackness of an ornamental spruce.

ACROSS the lawn an electric lantern flashed, and sent its sharp white beam straight toward “X” as its bearer came forward through the trees. The Agent darted to the left, moving with swift strides. He watched with relief as the light continued in the direction of the wall. But an instant later he heard a rustle in the dry grass behind him, and whirled to see phosphorescent eyes gleaming.

He crouched and waited as the dogs came toward him. There were at least four. They did not bark again. Trained watchdogs, they had been taught not to yelp at everything they saw. They would ring their quarry first, then give warning.

He heard the pad of feet, then saw their silhouettes against a street light shining over the wall. They were huge police dogs, ears alertly pricked, hackles stiff. Soon they would give tongue, or attack with flashing fangs.

But the Agent didn’t even feel for the only weapon he carried — his gas gun. Instead, he sent a low whistle into the night. It was the strange, weirdly melodious whistle of Secret Agent “X,” as eerie as the note of some wild thing.

The dogs stood still as though frozen. Then they approached him slowly, and he spoke to them with low, soothing words, holding out his hand. For a tense moment they held back, fangs bared and legs stiff. Then with a low whine the leader went forward. Agent “X” stroked the animal’s muzzle and at that sign of friendship, the others came close, too. The watchdogs set to guard Sully had become “X’s” friends.

An ironic smile twitched the Agent’s lips as he moved on toward the house. He was approaching with an escort, now. He could hear the man by the wall whistling, baffled by the disappearance of his dogs. But the great beasts preferred the company of their new-found friend to that of their master.

“X” SENT them away with a low-whispered command when he came close to the mansion. He could risk no sound from them, to interfere with the daring entrée he had planned.

As he stepped near the house, his fingers felt for the ingenious chromium tools and master keys hidden cunningly in secret pockets of his suit. Choosing an unlighted sun-porch at the building’s side, he had the door open in less than a minute and was tiptoeing across the porch in his rubber-soled shoes.

Before entering the door into the house itself, he drew a case strapped close against his thigh an instrument no larger than the smallest vest pocket camera. It looked so much like a camera that it would deceive anyone. But when he opened it, no lens or bellows showed. There was a small rubber disc and a coil of flexible cable inside instead.

He pressed the disc to the outside of the door, put the body of the instrument to his ear, and fingered what appeared to be a film wind. This was a delicate rheostat control. There was no film inside the thing, but small round batteries which seemed to correspond. In the Agent’s hand was the most compact and powerful sound amplifier in existence, a mechanism which he had worked out himself.

Carefully adjusting the rheostat control, he listened to various noises far in the interior of the big house. Somewhere footsteps sounded, but they were several rooms away. Voices came to him — but the thicknesses of intervening walls made the words too indistinct even for the instrument in his hands to clarify.

Convinced that no one was behind the door, he opened it quickly, entered, and found himself in a large music room. A grand piano stood against one wall. The Agent tiptoed toward it, blinked on his small light. Faint dust on the keys showed that the piano had not been used for months. This room, eloquent of the big parties Sully had indulged in in bygone days, was empty now. He had made a wise choice in entering it.

The Agent crossed it swiftly. Beyond, through heavy portieres, he came to a small reception room with a thick, soft carpet underfoot. There was a door at the end of this and a faint spot of light gleamed through the keyhole. Another door led to a wide hall, where he saw the faint glow of a shaded light. He moved toward this, then stopped abruptly. A board somewhere under the heavy carpet had squeaked under his stealthy tread.

The sound was faint, mouse-like, yet a shadow moved instantly in the hall. Agent “X” could see huge shoulders and a giant head thrown in black silhouette on the opposite wall. The shadow moved, changed size as the man behind it approached slowly.

Sucking breath between his teeth, the Agent backed into the shadows of the reception room. He crouched behind a chair and waited.

The shadow moved to the door, and the man was revealed in the subdued light behind him. Big, heavy-set, he had the flattened features of an ape. His head was bent forward on a thick, bull neck. Something in his fingers gleamed dully. An automatic — proving that this was one of Roswell Sully’s paid guards. The financier had taken a tip from the racketeers he resembled, had hired paid gunmen to protect him.

Agent “X” drew his gas gun from his pocket, but hesitated. He dared not use it now. The faint chemical smell of the gas might drift through the house and attract attention. It might arouse the suspicion of whoever was in the room behind the lighted keyhole. No, he could not use the gas gun, though it was his only weapon. As he waited, “X” heard voices raised in the room beyond. It made him tingle with excitement. He felt a stab of annoyance at this interruption.

The apelike gunman came through the door and moved stealthily toward a wall switch, obviously intending to flood the room with light. And that would not do! As the man’s fingers reached for the switch, “X” sprang.

He made two coordinated movements. He wrenched the gun from the giant’s hand and at the same moment clapped a palm over the mouth that parted to let out a bellow of surprise. Then, before the disarmed guard could begin a hand-to-hand struggle which might result in noise and the upset of all his carefully laid plans, Agent “X” doubled up his knuckles and delivered a famous jiu-jitsu blow — the deft thrust directly under the heart, as taught by Tatsuo Shima, instructor to the bodyguards of His Imperial Highness Hirohito in Tokyo. A man could be killed by that blow, or merely knocked insensible, and Agent “X” was a master of the lighter, stunning thrust.

The big guard went as limp as though a bullet had crashed into his brain, and “X” lowered his unconscious body to the carpet.

No noise had disturbed the quiet of the room, and the way was clear. Agent “X” tiptoed on toward that door from behind which came the sound of voices, one of which was harshly raised.

Chapter IX

THE loud voice was a man’s, the other a woman’s, and in the latter the Agent recognized the drawling, cultured accents of Vivian de Graf.

He tiptoed closer, found the door into the room slightly ajar, and cautiously widened the opening, bringing into his line of vision the couple at the far end of the room.

Vivian de Graf, sumptuously clad in furs, was seated in a deep, brocaded chair, her slim legs crossed, gloved hands toying with a jade cigarette holder. She looked utterly bored.

Roswell Sully stood before her. His face, with its clipped and bristling mustache, was red beneath its thatch of white hair. Anger showed in every line of his dapper figure. A big diamond on one well-manicured hand flashed as he gesticulated.

“Vivian — I can’t stand it!” he was saying thickly. “All afternoon I’ve been waiting, counting the minutes, expecting that you would keep your promise to stay and dine with me. Now you say you can give me only half an hour. Really, I—”

Vivian shrugged, sniffing delicately at the spotted orchid pinned to her coat. She spoke languidly: “Do you expect me to dance attendance on you all the time, Roswell?”

“All the time!” Sully’s voice rose jaggedly. “All the time — when you’ve only let me see you twice this week. To discuss business matters!”

Vivian de Graf fumbled in her bag, shrugged again. “A cigarette please, Roswell. I seem to have run out.”

Sully ignored her request. “You forget,” he went on furiously, “all I’ve done for you. The money you’ve made through me, the prestige my name has given you — the people you’ve met! What would you be without me? Nothing! And yet you—”

A sigh fell from Vivian de Graf’s lips. Without replying, she rose languorously and crossed with swaying hips to a table where she helped herself to a cigarette from a red lacquer box.

Sully stared at her insolently turned back. “By God, Vivian,” he began passionately, “if you’re playing around with some other man — If you leave me after all I’ve done for you, I’ll — I’ll—”

She turned slowly, touching a match to her cigarette. Her tapering fingers were steady. Her soft laughter was faintly derisive as she let smoke trickle from her nostrils.

“What?” The drawled word was a challenge. “What will you do, Roswell?”

“Kill you!” Sully shrieked. “Kill you — even if I go to the chair for it. Kill you — and tell the world what you are. A damn, calculating gold-digger!”

Vivian de Graf leaned against the table, and laughed in his face. “Kill me! You? Why — you haven’t that much nerve left! You’re afraid — afraid to leave this house. Even to show your face in the streets.”

Sully stepped close to her, his fingers raised and tensed as though he would clench them about the woman’s white throat; but his hands were shaking like withered leaves in a wind.

Vivian de Graf laughed again, but the amusement had left her voice. “Don’t be a fool! And don’t touch me! It’s you who are in debt to me. I’m a young woman and people say I’m beautiful. What have you to give me? You’re getting old, Roswell — old — old! If you must know, you bore me, and — I have other friends.”

Her words seemed to stun Sully. He stood swaying on his feet, staring at her. His clenched hands fell laxly at his sides.

Vivian de Graf ground out her cigarette, gathered her furs about her.

“Well, shall we say good-by?” She moved toward the door.

At that, a change came over Sully’s face. The red flush of anger faded, leaving it dead white. “Vivian — Vivian, for God’s sake don’t leave me like this! Forgive me for speaking as I did. I’m just an old fool. But I’m insane about you—” With frightened, abject remorse, Roswell Sully dropped suddenly to his knees, caught the hem of her dress, and kissed it.

Vivian twitched sharply away. “Don’t be dramatic, Sully,” she said scornfully. “It makes you ridiculous. And besides, it’s so — tiresome.” She walked away toward the door.

“X” QUICKLY left his observation post and slipped out of the house as he had entered it. He heard Sully’s voice still pleading as the front door opened. But Vivian de Graf went out and down the drive; her head arrogantly high.

“X” crossed the lawn to the wall, scaled it as he had before, and crouched in the shadows. Apparently, Vivian de Graf had a key to the gate, for it opened and closed silently, and she appeared in the street. There was the click of high heels as she walked toward her car.

Agent “X” edged nearer, silent as a shadow. He was debating whether to speak to the woman now, or follow her, when he drew in a sudden sharp breath. For some one else was watching Vivian de Graf.

Across the street another shadow had detached itself from the hedge bordering an estate opposite Sully’s. It moved cautiously along the walk, then started across the street toward the car. There was a furtive tenseness in the man’s movements. And something glittered in his hand.

Just as Vivian opened the door of her car, and was bending to climb in, the man sprang toward her. She turned her head and a startled, terrified cry came from her lips. She crouched as though she were facing a wild beast. The man’s arm drew back.

Agent “X” leaped forward out of the shadows like a hurtling catapult. His clenched fist struck at the thing gleaming in the man’s raised hand, sent it shattering to the street.

Vivian de Graf swayed against “X,” and while he steadied her the man ducked around the car like a startled rat and fled. The woman straightened then, and “X” sprang in pursuit of her attacker. The man had disappeared through the hedge across the street. When “X” pushed through, his quarry had lost himself in the dark maze of trees covering a wide lawn. The Agent knew there would be no use in further pursuit.

He went back to Vivian de Graf. Something had splashed onto his wrist from the thing in the man’s hand, and it burned like a spark of fire. He reached down to rub it off on a strip of grass by the curb, and his nostrils tingled with an acrid smell that rose from the sidewalk.

Vivian de Graf had regained her poise. Her dark eyes met his calmly. “Who are you?”

The Agent tapped his camera, smiled. “Just a newshound who happened to be passing. And it’s lucky I was!”

The woman poked with her toe at a jumble of broken glass on the sidewalk.

“What is that?”

“That,” said “X” gravely, “is acid. Somebody wanted to mar your beauty, I’m afraid.”

“Well—” her voice was cool, “you saved me from a nasty situation, anyway, and I want to thank you.”

“Aren’t you going to report this to the police? Do you know who that man was?”

Vivian de Graf’s laugh was mirthless and harsh. “An old — friend, I think. Drunk, probably.”

“Or just playful,” the Agent said sarcastically. She glanced at him sharply. His smile was disarming. He seemed to be merely a guileless young newspaperman. But the woman’s next words were tinged with suspicion.

“It occurs to me that it was rather odd — your being here just at the right moment.”

“X” THOUGHT quickly. This woman was shrewd. A display of frankness would be safest for him. He smiled again, showing even white teeth.

“Not as odd as you think, Mrs. de Graf, since I’ve been trailing you all afternoon.”

Dark eyes and arched brows questioned him.

“It’s that robbery at the bank,” he said. “You were there. I want your story of the thing — and a picture. It’ll get me in solid with the old man. How about it?”

His eyes bored into hers, trying to discover whether or not he had convinced her. But her eyes were inscrutable as she smiled and gestured toward her car.

“One good turn deserves another, I suppose,” she said lightly. “But we can’t stand here in the cold and talk. Hop in.”

There was a thin smile on the Agent’s lips as the phaeton purred downtown. Nothing could have pleased him more than this. He was alone with his suspect, in a position to study her closely. Already he had proof that she was a woman of startling poise and stamina. A woman cool-headed and callous enough to cast in her lot with criminals.

“Don’t forget,” he said eagerly, “that I want your picture. Society beauty tells story of bank holdup. That’s feature stuff. The crime has got the whole police force gaga. It’s a mystery, it doesn’t make sense — so it’s hot news.”

“But you, a bright young reporter, will solve the mystery of course.”

Her smile challenged him, mockery gleamed in her eyes. He was careful to stick to his role.

“I wouldn’t say that, Mrs. de Graf. It’s got me stumped, I’ll admit. But I’m going to take a whack at it.” He paused a moment. “You were there,” he added. “Haven’t you got some theory?”

She nodded. “Personally, I suspect that man Hearndon, who came into Banton’s office just before the raid.”

“I don’t know,” said the Agent. “The cops are looking for Hearndon — and Washington says there isn’t any such name on the Department of Justice list. He was a phony, all right, and yet—”

Grim amusement twitched the Agent’s lips in the semidarkness. What would Vivian de Graf do if she knew that “Hearndon” was sitting close beside her?

“There’s absolutely no doubt,” she said positively, “that Hearndon, whatever he was, acted as an advance scout for the gang. His coming was the signal for the raid to begin. That’s what I told the police when they questioned me.”

“But Hearndon wanted the bank closed! How would that have helped the crooks?”

The woman laughed softly. “Hearndon knew there wasn’t time to close the bank. That was only a stall. There are clever men behind this thing!”

THE phaeton sped across the city and entered a mews. It was close to the edge of a park, in an ultra-smart residential section liked by those who leaned toward the Bohemian. Wealthy actresses, painters and musicians had studios here.

Vivian de Graf stopped her car before a two-story building of pink stucco. It comprised two apartments, each with its private entrance. She had chosen a setting typical of a woman whose private life would not stand close inspection. An ideal residence, too, “X” thought, for a person who wished freedom to come and go unnoticed at any hour of the day or night.

With her own key, Vivian de Graf opened the door and showed “X” into a large, exotically furnished drawing room. Two blue vases filled with spotted yellow orchids caught the Agent’s quick eye instantly, one on top of a piano, another on an antique table. They added the final touch of the bizarre to this exotic and very expensively furnished room.

“You’ll have something to drink,” Vivian de Graf murmured as she slipped the soft mink cloak from her shoulders. “Some sherry, perhaps?” Her slim hand reached for a cut-glass decanter.

The Agent nodded. “Thanks.”

His eyes were alert. Something in the room seemed to hint at the crouching shadow of evil. The still draperies were too luxurious, the furnishings too expensive, this woman a bit too poised and casual. And those dozens of spotted orchids, which must be worth a small fortune, seemed the symbols of an unwholesome mystery.

He drew the nearest vase toward him and examined the heavy blossoms, with the eye of a connoisseur. He had never seen blooms like these before. He was familiar with most of the thousands of orchid species scattered throughout the world. He had thought all those in cultivation were known to him.

But these eluded classification. They reminded him of the Queen Cattleya orchids, yet were larger, deeper in their saffron tint. They bore some resemblance to Cyripedium Argus.

His eyes switched abruptly from the flowers to Vivian de Graf’s white hands. Almost unconsciously he had detected a minute but incongruous movement she had made. In pouring his glass of sherry she had let something fall into the wine — a few drops of colorless liquid from a ring. She had put either dope or poison into his drink!

Chapter X

NO slightest tremor of uneasiness showed in the Secret Agent’s manner. He was, in fact, elated at this development. Here was final proof that Vivian de Graf was a dangerous, unscrupulous woman. Her act was to him a tacit admission of her guilt. And in it he saw a great opportunity to make her betray herself further.

Doctored liquor was an old story to Secret Agent “X.” Once, long ago, in an espionage assignment against one of Europe’s most famous spies, such a trick had caught him unawares. Ever after that experience he had been on the lookout for a possible repetition of it, and had taken simple but adroit precautions to checkmate it without rousing suspicion.

Vivian de Graf was watching him through drooping lids. Her eyes were brightly alert behind them. Her white teeth showed in a flashing smile. Her graceful, supple figure was relaxed in her chair.

Before drinking his wine, “X” offered her a cigarette which she accepted. He struck a flame on the lighter Betty Dale had given him and which had served him so well in the burning house, touched it to Vivian de Graf’s cigarette and to his own, then returned the lighter to his pocket.

When his hand came out-again, something came with it — a small syringe of pliant rubber, like an old-fashioned camera bulb. To it was attached a tiny curved tube. “X” held the syringe cupped in his right palm, the third and fourth fingers pressed against it, while his second finger hid the tube.

Lifting the sherry glass in thumb and forefinger, he raised it to his lips. Then, as he tipped it slightly as though sipping, he let the tube’s end drop into it, releasing his two fingers on the syringe. The bulb at once began to fill. As the Agent tipped his head and the glass back farther, the sherry disappeared directly before Vivian de Graf’s eyes.

No one, save a person well versed in stage magic and sleight-of-hand, could have conceived that the wine had gone anywhere except into the Agent’s mouth. “X” had, in fact, learned the trick from a famous vaudeville magician.

He set the glass down, let his right hand fall to his side under the table, thrust the syringe back into his pocket and gave a twist to the tube which sealed it.

Vivian de Graf was smiling. “Now,” she said, “what about that picture you wanted — or were there some other questions you’d like to ask to round out your story?”

“Let’s see.” The Agent took out notebook and pencil. He made several notations, seeming absorbed in his work. He was conscious that Vivian de Graf was observing him, conscious of a new watchfulness in the woman’s eyes. There was a catlike quality in it that was definitely sinister.

This was a tense moment for the Agent. Perhaps some devilish, quick-acting poison had been dropped into his glass. Perhaps it had been only a drug. He did not know. He could only stage an act, and hope it would be convincing.

At the end of a few seconds he looked up from his notes, passed a slow hand across his forehead and blinked confusedly. “If you don’t mind repeating a few things,” he said. “I seem to have forgotten. Don’t know what’s the matter with my memory. This man Hearndon—”

He let his speech trail off, laughed as though in embarrassment. “Here — let’s see.” He made a few ineffectual dabs at his pad. He appeared to study them, but his head sank lower and lower. “Hearndon,” he muttered, “Hearn—”

His body swayed in the chair. He made a feeble, sleepy clutch at the edge of the table, slumping sidewise to the carpet. He lifted himself once feebly, then fell back and lay inert, every muscle lax.

His eyes were closed, his body limp, but his pulses were hammering. There was a chance he hadn’t manifested quite the right symptoms, that the woman’s suspicions had been aroused. Her silence made a breath-taking moment of suspense. She made no sound, said nothing for several seconds.

Then she rose and bent over him. Self-control was difficult for the Agent at that moment, the temptation to open his eyes at least a slit, almost overpowering. For all he knew, Vivian de Graf might be planning to jab a knife into him. But a moment later she moved away across the carpeted floor.

SHE picked up a telephone and dialed a number. Agent “X” listened intently. His ruse had worked. Vivian de Graf thought him unconscious or dead, and her next move should betray her further.

Her voice came to him. “Lorenzo — this is Vivian. Please drop over, at once! There’s something that may be rather important.”

Lorenzo! The Agent’s heart beat fast. Through his act of appearing to swallow the drug it seemed he was about to meet some one else closely connected with the criminal gang. Vivian de Graf’s whole manner during the last hour had served to convince him that his first suspicion of her had been right.

He lay quietly, apparently in the depths of dreamless unconsciousness, when the woman returned to her seat. She hummed a few bars of a popular song with astounding casualness. She had jilted a wealthy lover of years’ standing, she had had acid thrown in her face, she had given another man drugged wine — yet she could sing! Here was a woman of the temperament and caliber of the Borgias.

She went into an adjoining room, leaving the door open. “X” could hear the soft rustle of feminine garments. Then she returned, settled herself in a chair and idly flipped the pages of a magazine. Shortly afterward a buzzer sounded, two short notes, a long, and another short.

Vivian de Graf crossed quickly to the door, opened it and said: “Come in, Lorenzo.”

Agent “X” heard a man’s tread. He slitted one eye and stared toward the door in time to see a man enter. He was about thirty, smooth-shaven, suave, with sleek black hair. But his features bore the lines and blotches of dissipation, making him look older.

He started at sight of “X’s” body, then gave a lop-sided smile. The door closed and Vivian de Graf said casually, “Just a friend who dropped in, Lorenzo. He’s had one drink too many. You see the result.”

“Up to your old tricks, Vivian,” said the man called Lorenzo. “Just what does it mean?”

“Never mind now!” There was a note of authority in Vivian’s voice, as though she were accustomed to getting her way with men. “Take him out of here at once — and when he has recovered, it might be well to question him. He was very helpful, tonight — overly solicitous of my welfare. And when people get that way I’m always — well, suspicious!”

The young man with the gleaming black hair laughed again. “Aren’t you going to offer me a drink, too, Vivian?” His tone was caressing.

“This is not a social visit,” the woman answered icily. “Quick — get him out of here. Some one might come!”

LORENZO approached “X,” placed hands upon his shoulders and began shaking roughly. This gave the Agent his cue. He was not supposed to be poisoned, only drugged — and evidently, with some drug from which he could be aroused.

He sighed, stirred faintly, letting his head flop as Lorenzo shook him, manifesting the sluggishness of a man in a chloral hydrate coma. Lorenzo lifted him to his feet, and Agent “X” shuffled feebly, moving like a sleep-walker.

Vivian flung the door wide and Lorenzo marched his charge out to a waiting car. Agent “X” stumbled, almost fell, letting one knee strike realistically against the car’s door. Lorenzo bundled him in, slammed the door after him, and went round to the driver’s seat.

Gears clicked, the car purred away, with Lorenzo driving carelessly and Agent “X” slumped in the seat, breathing heavily. But his eyes were open now. If Lorenzo had turned to scrutinize him in the darkness he would have beheld not a stupefied man, but one whose gaze was brightly, speculatively alert.

The car turned out of an avenue, into a street where the lights were far apart and shadows lay heavily. “X’s” right hand began creeping toward a secret pocket in his suit. He was reaching for the compact gas gun that could knock a man out within a radius of twenty feet — one of the Agent’s most useful, non-lethal weapons.

But just then a car came out of a side street, and as it passed the interior of Lorenzo’s car was brightly illuminated. In that instant the man detected the change in “X’s” attitude. He gave a stifled exclamation, applied the brakes, and whirled toward “X.” One hand clamped over “X’s” arm, the other doubled into a fist to drive a blow into the Agent’s face.

Rubber squealed beneath the car. The vehicle lurched dangerously, threatened to plunge across the sidewalk into a fence. Even at that moment Agent “X” had presence of mind enough to twist the wheel, while he warded off Lorenzo’s blow with a deft twist of his head and a countering left. The car came to a stop, slewed around, and as it stood crazily across the curb in the shadows, a short, fierce struggle was waged within it.

Lorenzo proved himself a fierce fighter. He was angry, frightened, and he fought with the ferocity of a cornered animal, using every savage trick he knew. He tried to twist over and ram a knee into the Agent’s groin. He gave the Agent no time to pull the gas gun from his pocket. But neither could he draw his own automatic which made a bulge under his armpit. It was a battle of wrenching hands and knotted fists.

Once again, “X” resorted to a Jiu-jutsu blow. Any moment the queer position of the car and the struggling figures in it might attract attention. A patrol police cruiser might come along. Agent “X” could afford to take no chances with his prize.

His knuckles struck Lorenzo on the side of the neck. The man’s head jerked up spasmodically, his hands clawed frantically at his throat, his tongue protruded. For a moment he was like a man choking. The blow the Agent had given him was the well-known strangling blow, which temporarily cuts off air in the windpipe.

It gave the Agent time to do what he wanted. He drew his gas pistol from his pocket, took a deep breath himself, and then calmly fired full into Lorenzo’s face.

The man’s body slumped limply, and Agent “X” quickly cranked down the windows of the car, letting a draft blow through. He held his breath for nearly two minutes. By that time the gas inside the car had dissipated into a mere chemical odor.

He climbed out, pulled Lorenzo’s body from under the wheel, shoved it where his own had been, and took the wheel himself.

Agent “X” was now in complete command of the situation, and with his unconscious burden, in a confiscated car, he drove swiftly away into the night.

Chapter XI

THE Agent drove down a wide avenue, twisted through a maze of streets, turned into the driveway of an old suburban house. The houses on both sides were shuttered and vacant. Under an assumed name Agent “X” had rented this place as a convenient hideout. It had certain special qualifications.

He got out, opened the garage door, and drove in, closing the door after him. At the side of the garage was a doorway leading directly to the house. This was what made it useful to the Agent. Several times in the past he had carried unconscious bodies through that passageway, as he now carried Lorenzo.

Depositing the man on a couch in a room with drawn shutters, Agent “X” clicked on an overhead light. He went quickly through the man’s pockets, found a wallet with an identification card, and nodded to himself. His own encyclopedic memory supplied the details the card lacked.

The man before him was Lorenzo Courtney, black sheep son of a once wealthy family. There had been a time when a Courtney had sat on the board of every bank in the city. The family had died off gradually, leaving only Lorenzo, the spoiled and pampered darling of a doting widowed mother. He had joined a banking firm like the other members of his family before him; but the bank had been one of the first to collapse in the depression. Courtney, like old Roswell Sully, had been disgraced in the public eye.

Leaving his captive on the couch, Agent “X” drew elaborate equipment from a cabinet. This included special lights, photographic apparatus, a sound-recording mechanism and a fingerprint set. He set the articles up one by one, ranged around Courtney, prepared to make a more complete study of the man than he would undergo even at police headquarters. He was going to force Courtney to talk. The private third degree through which he was about to put him would bring out whatever the man knew about the criminal band. Ruthless, unconventional measures were justified in the face of such horror as had occurred outside the looted banks.

He forced liquid stimulant between Courtney’s lips to offset the effects of the gas. When Courtney stirred, the Agent propped him in a chair, facing the battery of lights. Then he turned on the silent mechanism of his phonographic device. A stylus would make a permanent record of Lorenzo Courtney’s voice.

Courtney opened his eyes at length. He was confused for a full minute. Then his gaze focused on the stern face before him, and he gave a visible start. A curse came from his lips. He tensed as though to leap from the chair, but the Agent stopped him with a sentence.

“Stay where you are, Courtney!”

The voice of the Agent had a compelling ring, and Courtney seemed to freeze. Then his eyes became combative. But he didn’t move, not with the odd, magnetic gaze of the Secret Agent fixed upon him, not in this room which seemed to speak of mystery and power.

“Who are you?” he asked harshly. “Why did you bring me here? What do you want of me?”

A laugh devoid of humor sounded in the room — the harsh laugh of Secret Agent “X”. Then he said: “A half hour of your time, Courtney, and the answers to the questions I shall ask.”

Courtney’s eyelids narrowed. He was fully awake now. “So,” he said. “Vivian de Graf had a right to be suspicious of you. You are a detective?”

Agent “X’s” reply was stern. “I’m the one who will ask questions. You are to do the answering.”

Courtney’s glance flashed around the room. He saw that the Agent held no gun on him, yet he appeared to realize that he couldn’t escape. His voice was hoarse when he spoke again.

“This isn’t police headquarters,” he said. “You are not—” He didn’t finish the sentence. He let his voice trail off. His belligerence slowly vanished. And his face became mottled with the pallor of fear, while into his eyes crept a look of awe. “You—” he stammered. “You—”

The Agent smiled with thin lips. “Quiet, Courtney! Listen to what I have to say.”

A cry burst abruptly from Courtney’s lips; a cry of despair and terror. “I understand,” he cried. “I understand! You are the man they call — Secret Agent ‘X’!”

THERE was tense silence in the room. The Agent didn’t reply, and Courtney took his silence for assent. The banker’s hand darted abruptly to his breast pocket. Two fingers disappeared, and came out clutching a white capsule no larger than a bean.

“X” leaped forward, but not quite soon enough. For Courtney had thrust the white object into his mouth. He had clenched his teeth over it, swallowed — and he broke suddenly into a peal of wild laughter.

For an instant Agent “X” stared at the man. Then he sprang toward a small medicine cabinet containing antidotal drugs. He knew what Lorenzo Courtney had done, knew that the capsule must have contained poison. But when he turned with a bottle in his hand, he saw he was too late.

For there were beads of perspiration on Courtney’s forehead already, and his skin was turning gray. From his open lips came the pungent smell of bitter almonds, an odor Agent “X” had sniffed before. Courtney had swallowed deadly cyanide, had taken his own life, and nothing any man could do now could stop the inroad of that terrible poison, already saturating his system.

His breath came in labored gasps, his hideous laughter rang out again, and there was an expression of malicious triumph in his eyes as he stared at “X.”

“You’ll never — know!” he suddenly screamed. “You’ll never — know — now—”

His head fell sidewise. He jerked off the couch, twitched on the floor in racking spasms, then lay still. When Agent “X” stooped over him to feel his pulse, there was no flutter beneath his fingers. The man was dead.

Bitter disappointment made the Agent’s eyes bleakly grim. He had felt certain this man was a member of the bandit gang. Now Courtney’s lips were sealed forever. Now no third degree could sweat secrets from them.

Yet the Agent did not give up hope. Something of value might be salvaged from the wreck of his plans. He went quickly to work. Time — that was the big factor now. Time — before the makers of darkness had worked still more havoc in the city, before others met such a fate as Ellen Dowe.

Already Lorenzo Courtney’s features were changing perceptibly, showing the first masklike aspects of death. The Agent, moving tensely, propped the dead man up with pillows, focused the powerful mercury vapor light upon him. He set up his camera, thrust in a holder of achromatic plates, took pictures of Courtney’s features from many angles. Then he made a series of careful measurements and fingerprints, piled them and the plates away to be developed as soon as he had time. He thrust Courtney out of sight in a coffinlike compartment under the couch, changed his disguise to that of A. J. Martin, and quickly left the hideout.

Back in Martin’s office, “X” sent grim orders over the telephone to Hobart. Other orders clicked over the air in the special code signal that would reach Harry Bates.

“Drop present work. Rush through secret investigation of Lorenzo Courtney, ex-banker. Get information concerning friends, clubs, personal habits. Rush this to me!”

He sat for a moment in intense concentration, then with a decisive motion picked up a volume of “Who’s Who” from his desk. He flipped it open, turned to the “D’s,” scanned the columns, and stopped at “De Graf, Emil.” The paragraph beneath this name read:

A city directory passed next through the Agent’s hands. Once again he found the name de Graf, then left his office quickly and sped across town in his car.

FOR the moment he was not concerned with the beautiful Vivian de Graf. It was her scholarly husband whom he sought, the man who spent his time in classroom and laboratory, experimenting with the mysteries of the universe, while his wife experimented with human emotions.

There was a compelling double motive behind the Agent’s desire to talk to Emil de Graf. In the first place, the man was Vivian de Graf s husband. In addition to that, he was a brilliant and original worker in experimental science. He must have some theory concerning such a phenomenon as this weird darkness which had been used as a cloak for crime.

The Agent’s mouth was grim. He felt he was working in a darkness almost as impenetrable as that which the raiders so mysteriously created. Never had he encountered any crime quite so baffling.

Two things he must find out, before he could combat it. One, the identity of the men who operated behind the weird darkness; the other, how that darkness was created. He knew now from Thaddeus Penny’s statements and from the pictures Hobart had made, that the sun shone even while the darkness fell — two inconsistent happenings which nevertheless formed a theory in the Agent’s mind.

The address given in the directory proved to be an ancient, brownstone house — a very different residence from the pink stucco apartment which Vivian de Graf maintained separately.

A slatternly servant on squeaking shoes let the Agent into a hall that smelled of dust and mothballs. She bade him wait, squeaked off into the rear of the house and returned in two minutes.

“The professor will see you. This way if you please.”

The rear room, converted into a laboratory, where de Graf worked, was as modern as the rest of the house was ancient. Gleaming scientific instruments stood about. Shelves of books on mathematics, chemistry, astronomy and physics lined the walls. A man with a thin face and stooped shoulders came forward, peering at “X”. He had faded blue eyes, a vaguely sweet smile. He extended a dry, cold hand, said:

“Yes. What can I do for you? I didn’t catch the name?”

Agent “X” studied the man for a second. It was hard to picture the dazzling Vivian de Graf married to such a person. One of nature’s little jokes that these two had been thrown together — the withered student and the gorgeous butterfly. The Agent handed his card, bearing the name A. J. Martin, to de Graf.

“From the press,” he said. “I wanted to ask you a few questions about a thing which vitally concerns the public at the moment.”

Emil de Graf made a weary, harried gesture. “I’m sorry — please! I never like to give out statements of my experiments except to authenticated scientific journals. No offense meant, but the newspapers have a way of misquoting, you know. Most embarrassing.”

The Secret Agent interrupted. “This is not about your work. Perhaps you don’t read the papers, but you must have heard of a bank robbery that took place today under odd circumstances — after the coming of darkness.”

“Darkness,” echoed de Graf. “Of course. I heard some of my students talking about it. But really, I’m not interested in crime.”

The Agent was watching the professor intently. De Grafs eyes were vague, expressionless. No sign of emotion was betrayed in the thin face.

“You’re a scientist,” “X” said. “Have you no theories as to how such darkness might be created? A statement from you would be interesting.”

De Graf laughed wearily. “Interesting perhaps to a thrill-seeking public. But hardly to scientific men, for I have made no study of this darkness you speak of. I don’t—”

The Agent cut him short again, a frown of annoyance on his face. De Graf’s attitude was irritating. “Since your own wife was at the scene of the crime I thought perhaps—” the Agent began.

DE GRAF chuckled. “Vivian, of course! A woman with very modern ideas, but still a child at heart. Full of zest, always getting herself into predicaments. We understand each other perfectly, she and I.”

“Then you have no statement to make about this darkness?”

De Graf waved his hand. “My dear fellow, if I had any, you as a layman would hardly understand it! But, as I said, I have no interest—”

The Agent saw the uselessness of talking to the man. He thanked him and left.

But as he drove away, “X” found a vague suspicion gnawing at his mind. De Graf had been almost too offhand. Even though he were a man lost in a world of experiment and theory, it seemed incredible that any scientist could feel such utter lack of interest in a phenomenon so directly allied to his own field.

The Agent had sensed strong undercurrents in the man’s personality. De Graf was the suppressed type, of course, one whose brain had driven human emotion into the background. But emotion was there, lurking. And there was no saying into what strange channels it might be diverted. The Agent decided to order Hobart to have a man keep track of the scientist’s comings and goings.

Two hours later “X” had received reports on Lorenzo Courtney from both his investigating groups. These reports were not as complete as he would have liked. Yet they contained much valuable information. It would take days or weeks to unearth all the details of Courtney’s life.

The whole matter of the dead man’s connection with a crashed bank was there. Hobart had sent him a newspaper clipping including a statement made by Norman Coe, head of the Citizens Banking Committee, giving the details which had caused Courtney’s indictment before a grand jury.

This statement proved conclusively that even at that period of his life Courtney had gone in for unethical practices. He had taken part in the misappropriation of depositors’ money. He was on his way to becoming a criminal then.

And the reports from his two investigating groups had given “X” a list of Courtney’s friends, of the clubs he frequented, the restaurants he patronized, the names of his tailor, his barber, his doctor. Bates and Hobart had done good work. Until a counter order from “X” stopped them they would go on collecting data until a clear picture of the man had been constructed.

But “X” could not wait longer. Every hour that passed complicated the difficulties of the situation. Courtney was dead, and those interested in his welfare might wonder where he had disappeared, grow suspicious. That must not happen.

Eyes staring into the dark streets before him, hands clutching the wheel of his car. Agent “X” drove back to the secret hideout where Courtney’s body lay. He had a plan in mind — a scheme that no other investigator of crime would have thought of, much less undertaken. This was to create a disguise more daring, one fraught with greater possibilities of danger, than any he had attempted in his whole career — the disguise of Lorenzo Courtney.

Chapter XII

IN the seclusion of his hideout he set feverishly to work. A small electric clock on a shelf marked off the seconds, warning “X” that the thing he planned was dependent more than anything else on time. The impersonation he was about to make was not like the stock disguises he had used many times before.

To create this disguise, all his artistry, all the amazing scientific skill of the Man of a Thousand Faces, was required. Lorenzo Courtney’s features had changed completely now. Rigor mortis had set in. The face of the sleekly groomed ex-banker had the masklike rigidity, the pinched nostrils, the sunken cheeks of death. The strong mineral poison he had taken had added a horrible grayish hue to his face. Courtney could not now be used as a pattern for disguise.

The Agent quickly developed the plates he had made, set them with special fixative, dried them in a fan dryer, and made quick prints.

Then, after removing Courtney’s outer clothing, he put the body back into the recess under the couch. In creating this disguise he preferred to make use of his prints and measurements, and his own graphic impressions of the man in life.

While his long fingers worked their magic, he turned on the phonographic record of Courtney’s last speech.

Then his own lips moved. He was imitating the sound of Courtney’s voice, the suave English accent that the banker had affected.

He imitated the man’s features on his own face, slipped a black toupee over his own brown hair, carefully combed the artificial locks until they duplicated the lustrous blackness that had crowned Courtney’s head.

For seconds after the disguise seemed complete, he worked on, adding the deft touches that distinguished his masterly impersonations from the crude attempts of other investigators. The tiny lines, the moles, the slight skin blemishes that made the disguise perfect.

When he arose and donned Courtney’s clothing, the effect was weirdly startling. The dead man seemed to have come to life in the room. Fate had played into “X’s” hands to the extent of making Courtney as tall and broad-shouldered as himself. The only point in this strange case where Fate had chosen to be kind, and that kindness might lead the Agent to his death.

For his data concerning Courtney was still incomplete. Never had he undertaken an impersonation upon which so much depended, armed with less information about the man he was impersonating. The outward perfection of his disguise was the one thing he could depend on. For the rest, he must trust to his wits.

Among the facts Jim Hobart had sent him were the two addresses Lorenzo Courtney maintained. One, the old-fashioned brick mansion on a fashionable avenue where his mother reigned like a dowager empress; the other, Courtney’s bachelor apartment.

“X” had quietly confiscated the contents of Courtney’s pockets. A wallet, containing a roll of bills and an uncashed allowance check from his mother. Cards to several exclusive clubs. A ring with more than a dozen keys on it.

“X” LEFT his hideout, carefully keeping to the shadows and cutting across two vacant lots till he reached another street. Here he walked several blocks before summoning a taxi. The address he gave the driver was that of Courtney’s apartment.

The place, when he reached it, was very much as “X” had visioned it — a flamboyant suite of chambers in an ultra-smart building. A dizzy blonde at the telephone desk nodded at him. There was a flash in her eyes and a knowing moue of her red lips that seemed to speak of intimate acquaintance. The Agent returned her smile with a wink. He said: “Good evening,” to the elevator boy, and ascended to Courtney’s floor.

The shape of the keyhole told “X” which key on Courtney’s ring would fit the lock. He opened the door, entered, and listened a moment to see if there were anyone about. Courtney might have a servant. But none appeared. And “X” saw a moment later that the kitchenette and serving pantry showed lack of use.

He became tensely active at once. The hungry gleam of the quest was in his eyes. A small secretary with locked drawers stood at one side of the living room near a luxurious davenport. The Agent opened this quickly and searched it, but found nothing save many letters addressed in various types of feminine hand-writing.

He cast these impatiently aside. He wasn’t interested in Courtney’s affaires de coeur. What he wanted was some clue to the man’s criminal activities.

He began a quick, deft search of the whole apartment. This was routine work for a man who had been associated with criminals and their ways for years. Systematically, thoroughly, he went over the room, examining the walls first, tapping them for hidden compartments, lifting rugs, scrutinizing furniture.

His search was half completed when he came to a handsome antique straight-backed chair covered in rich tapestry. An irregularity in this caught his eye — a tiny roughness on one leg, below and behind the seat. He turned the chair around and found a corresponding rough spot on the other side. The varnished finish did not quite match. With his knife blade, “X” probed, and the varnish came loose to reveal a circle of plastic wood.

He turned the chair over. Its bottom had nothing to attract attention — ordinary black cloth covered the webbing over the springs. But his fingers felt along it, and encountered an unnatural piece of metal. He pressed it. Something clicked. He turned the chair upright again, pushed up on the seat, and gave an exclamation of satisfaction. The seat, he found, was held by pivots hidden beneath the plastic wood, and formed the top of a small box, in which lay several objects.

One of these held the Agent’s fascinated gaze. It lay there like a coiled snake about to spring — a rawhide whip of pliant leather. The end of it was divided into three small lashes, each tipped with steel like one of the old-time cat-o’-nine-tails. And there were brownish smears on one of the tips. Dried human blood.

Here was one of the terrible whips that had been used on men and women as though they had been cattle. Here was concrete proof that Courtney had been a member of the band.

The Agent thrust the whip aside and drew out what lay beneath it, his eyes glittering with excitement. For he now held in his hand a mask of black cloth. But a quick examination of it brought disappointment and a puzzled look to the Agent’s eager eyes. There was nothing covering the eyeholes, no goggles like those he had felt on the man he had fought in the bank, and seen so graphically in the shots of Hobart’s film. This mask was of plain black silk.

TWO GUNS, a small blackjack, and a compact set of burglar tools completed the contents of the box. Courtney’s hidden equipment alone was enough to convict a man of felony.

Then the sharp ringing of the telephone interrupted “X’s” search. He answered it instantly, using Courtney’s suave voice. It was a girl, one of Courtney’s “big moments,” judging from her petulant complaints. When was he going to see her? Why had he neglected her? Why hadn’t he answered her letters?

Playing the role of Courtney, “X” stalled. Business matters had kept him occupied. He had been called out of town suddenly. He had not forgotten her. He finally stilled the girl’s syrupy gushings and hung up.

He continued his search of the apartment, overlooking no possible hiding place, until he had convinced himself that he had found Courtney’s only secret cache. The man evidently did not possess one of the mysterious helmets which enabled the members of the bandit gang to see in the darkness. And this puzzled Agent “X.”

He closed the secret box in the chair, paced the apartment for a time. Two courses were now open. He could wait here till something of importance reached him, some clue to Courtney’s activities; or he could move as Courtney through the clubs and restaurants where the young banker had been an habitué. The first plan seemed more logical. This was Courtney’s private retreat. He would receive important messages here, surely. But the inactivity of waiting tore at the Agent’s nerves.

In a fever of impatience he continued his pacing of the room. Three more calls came, all from women. “X” listened to each intently, weighing every word spoken in the hope that there would be some inkling of Courtney’s connection with the gang. There was not; and Agent “X” began to wonder if he had pursued the right course.

Frequently in his life great issues had depended on guesswork, hunches. More than once the uncanny correctness of his hunches had brought him success. Now, his instinct told him that sooner or later information of value would reach him at this apartment. But his senses cried out for action; his imagination painted ghastly pictures of what might be taking place outside, even at this moment.

At eleven o’clock, after he had been tempted a dozen times to leave the place, the telephone in Courtney’s apartment rang for the fifth time since his entrance. And now it was no feminine voice that greeted him.

His fingers tensed over the receiver as a slightly muffled man’s voice sounded. Agent “X” got the impression that the person was talking through a cloth, to disguise his speech. “X” crouched eagerly over the instrument.

“Courtney?” the voice said.

“Yes — Courtney speaking,” the Agent replied.

A slight pause. Then a muffled voice made a sudden, clipped statement in a tone of dry authority. A statement that brought a thrill to the Secret Agent’s taut nerves.

“We meet at twelve. I shall expect you, Lorenzo Courtney.”

Chapter XIII

NO OTHER word was spoken. The muffled voice was silent. The receiver clicked up. But Agent “X,” turning in taut excitement from the phone, no longer wondered if his decision to remain in Courtney’s apartment had been wise. He knew it had been, for there was every reason to believe that the man to whom he had just listened was the leader of the devil-dark gang.

Yet the message had been too brief to be satisfactory. Members of the band who used scourging, torturing whips to clear the way for their criminal activities were meeting at midnight. But where?

“X” was aware suddenly of his perilous lack of information concerning Courtney; aware of the difficulties the man’s self-inflicted death had thrown in his way. Courtney’s hideously mocking laughter seemed to ring in his ears. Courtney’s dying words echoed in his mind. “You will never know — now—”

Agent “X” walked to the secretary in Courtney’s apartment, sat down for a moment and studied the itemized reports that Bates and Hobart had rushed to him. The list of young Courtney’s friends held his attention.

Certain characteristics of the devil-dark criminals were known to “X” now. They were not ordinary underworld characters. They did not haunt the murky byways of crookdom. That was why neither Bates, nor Hobart, nor the police had been able to pick up details concerning them. And Thaddeus Penny had corroborated “X’s” own impression that the mysterious raiders were men of education, even culture.

“X” had a theory to explain this. Lorenzo Courtney had been living proof of his theory. Educated, well-bred men did not go in for crime generally unless other customary fields of activity were closed to them. Courtney had been a failure in banking. He had left his profession in disgrace, with the threat of a prison sentence hanging like a shadow over his life. He had been greedy, ambitious, vain at heart. Failure, disgrace, had brought out the innate criminal instincts that lurk in many men. The same forces would bring out those characteristics in others.

And on the list of Courtney’s friends which Hobart had given him was one which a card in Courtney’s wallet also showed. This was a man named Chauncey Doeg, a man who, according to Hobart’s data, had even served a two-year sentence for defrauding the mails in connection with the advertising of a certain bond issue. Doeg, like Courtney, had been a member of the younger sporting set, a polo player, yachtsman, and society gallant, much sought after by the mothers of debutantes, until disgrace had clouded his life.

Disgrace, obscurity, would be bitter pills for such a man to swallow; for the most intolerable poverty of all to bear is the poverty of those who have once possessed regal luxury.

Secret Agent “X” struck the secretary sharply with a clenched fist. His eyes were gleaming with the quest again. His logical brain had unearthed the possible hidden seeds of crime. He had made his decision — and was ready once more to gamble. But before he left Courtney’s apartment he did an odd thing for Agent “X.” He went to a glass decanter, poured himself a drink of whiskey and tossed it off. This was not because he needed stimulant. It was to make his disguise of the wastrel Courtney even more complete, by adding the odor of liquor on his breath. Twenty minutes later a car slowed and stopped at the corner of a block of shabby apartments. Agent “X,” still disguised as Courtney, was behind the wheel. He got out, sauntered halfway down the block, and merged suddenly with the black shadows at the mouth of a tradesmen’s entry. Here, with a view of the buildings on the street’s opposite side, he waited. One of those buildings held the apartment of Chauncey Doeg. And “X” had taken pains to learn that the banker was at home. He had asked Betty Dale, the one girl in the city who knew the true nature of his daring work, to call Doeg’s number. She had been instructed by the Agent to ask for “Charles Doeg,” then apologize timidly for calling the wrong party. She had reported to “X” that Chauncey Doeg was home.

“X” WAITED now with a feeling of impatience, a feeling of uncertainty that he had to fight down, akin to the same emotion he had had in Courtney’s apartment. Yet now it was even worse. For he had definite information that there was a secret meeting tonight. And, if his surmise concerning Doeg was wrong, the knowledge that the meeting had passed without his attendance would be intolerably bitter.

Yet all the facts pointed toward the verification of the Agent’s theory. These shabby apartments where Doeg dwelt proved that the once prosperous banker had come down in the world. He had had no doting and wealthy mother like Courtney to give him an allowance. If Courtney had been tempted into crime, how much greater must the temptation of Doeg be? And “X,” in his conversation with Betty Dale, had made quick check-up on the man. She was in a position to know, and she had given him certain facts.

Doeg’s character had changed since his stay in prison. He had become silent, irritable, appearing only in fashionable circles, and then to attend the wedding of a boyhood friend. For the rest he kept to himself, brooding apparently over his grievances.

But minutes ticked by, and the Agent’s uneasiness grew. He looked at his watch. Eleven thirty, and still no sign of Chauncey Doeg.

It wasn’t till twenty minutes of twelve that a heavy-set figure appeared in the vestibule of the apartment opposite. A shabby coat of a once modish and expensive cut fitted powerful shoulders. Above a white silk scarf a brutally aggressive chin showed, framing the thick lips of a sullen mouth. “X” recognized Chauncey Doeg from the minute description Betty Dale had given him.

The young ex-banker peered up and down the block for a moment. Then he stepped imperiously to the curb and summoned a passing taxi.

“X” left his hideout as soon as the taxi’s tail-light was a disappearing red eye dawn the street. He walked swift strides to his own coupé, made a U-turn and followed the cab, careful not to get too close.

Once, to avert any possible suspicion in Doeg’s mind that he was being followed, “X” took a chance, speeded up and plunged into a right-angle street. Then he swerved around a corner, raced along a parallel block and came back in on the route that Doeg’s taxi was following.

When “X” saw Doeg’s taxi draw to the curb he was a good two blocks behind. He immediately plunged into a side street, parked out of sight and reappeared on foot. Doeg must not see him. He would certainly think it odd that his friend, Lorenzo Courtney, was shadowing him.

So skillful had the Agent’s maneuvers been that Doeg was unaware that he was under surveillance. He moved with a lumbering, bearlike stride on along the street, in the same direction that the taxi had been following. At the next corner he turned left, walked two blocks till he came to a section of small shops and old-fashioned brick dwellings, and paused before a cast-iron fence.

Now for the first time he manifested furtive caution. “X” had ducked out of sight in an areaway. From the shadows of this he saw Doeg survey the street in all directions. Then Doeg ran quickly up the front steps of a shuttered house and plunged a key into a lock. An instant later he disappeared from sight.

The Agent waited a full minute. He looked at his watch again. It was now eight minutes of twelve. He came from his hiding place, moved almost invisibly in the shadows, walked around a full block and approached the house which Doeg had entered from the other direction.

Ascending the steps briskly as Doeg had done he made a quick examination of the lock. He had his special chromium tools with him, was prepared to use them if necessary, but he saw at once that an odd-shaped key on Lorenzo Courtney’s ring fitted this door.

In a moment he had opened it and was inside the mysterious house. No slightest sound reached his ears. He waited a moment, then drew his cameralike sound-amplifying mechanism out. To be caught with that in his hand would be to attract certain suspicion and attack if he were seen. But a blundering examination of the building would be equally as bad.

He pressed the disc-shaped microphone to the wall, heard a faint sound and, kneeling, shifted it to the floor. Now footsteps reached his ears plainly. They moved for some time as he listened, grew fainter and fainter, as though they were traversing a corridor or passage. They were obviously on a lower level than himself.

THE AGENT moved down a rear stairway to the basement floor of the house. He was now in a room similar to that of the house where he had almost burned to death.

He pressed his microphone to the floor again, heard the footsteps on a still lower level. His eyes widened. He strode at once to a cellar door, which the shifting beam of his flashlight revealed.

He didn’t need his microphone to guide him now. The dust of these cellar stairs had been disturbed. So had the dust on the cellar floor of this supposedly empty house. Many footprints were visible to the sharp, highly trained eyes of the Secret Agent. Many footprints all leading in the same direction. He followed them across the chamber till they ended close to a seemingly blank wall.

But there were cracks in the plaster before him, and a spot at his feet showed a jumble of ancient iron pipes where the house water connected with the city’s main. There was a shut-off here with a bent handle.

The Agent pressed against the wall ahead of him. It appeared to be rigidly solid. Here was an incomprehensive mystery, a point which might have stopped him — if he had not listened to those retreating footsteps through the earpiece of his sensitive amplifier. But men did not walk through solid walls.

He looked for hidden keyholes, found none. Then made a careful examination of the pipes, till he came to the apparent cut-off. Tentatively he turned this, half expecting to hear the swish and gurgle of water in ancient, rusty pipes. None came, but there was a distinct metallic click, and the solid appearing wall before him seemed suddenly to shiver.

The Agent pressed it again, and now a section of the wall turned on a pivot disclosing a jagged, lopsided doorway, cleverly following the haphazard line of the cracks. The cut-off had been contrived into a simple but effective lock.

The Agent closed the strange door behind him as Doeg must have done, walked on across another cellar room. This time the footprints visible to the Agent’s trained eyes led to a coal bin and disappeared. He plunged through the narrow door of the bin, and saw at once that the square piece of boarding at one corner must be the top of a trapdoor. There was no other possible exit from the coal bin except the window to the street chute, and that was thick with dust.

His questing fingers found a keyhole at the side of the boarding, which another key on Courtney’s ring fitted. He thrust it in, lifted the board cover, and descended a flight of steps. The weight of the cover surprised him till he looked up and saw that it was sheathed on the inside with heavy armor plate.

At the bottom of the steps he found himself in the passage along which Chauncey Doeg’s feet had echoed. His pulses were hammering with excitement. He had seemingly entered a bizarre and fantastic world of secret crime beneath the city’s peaceful life. And these precautions, the hidden doors, the subway-like passages, spoke of infinite power and cunning. The sides of the small passage he was in, hewn from the clay soil beneath the houses, were not fresh. They were at least a month or two old, proving that the brain or brains behind the devil-dark band had plotted crime long in advance of the actual commission.

But the Agent did not pause. Somewhere ahead of him he knew a password would be demanded of him surely — one that he did not know. But his quick brain had devised a daring answer, and he was glad that he had the smell of Courtney’s whiskey on his breath.

The passage curved beneath the ground, till Agent “X” in his excitement lost all sense of direction. The evident premeditation of the thing appalled him. What chance had society against such cunning, ruthless criminals armed with such a weapon as the strange darkness? The average evil-doer would consider a catacomb like this a rare feat. It was only a secondary precaution of the devil-dark gang.

At last the long curving passage ended in another stone wall with a steel door set in it. Here was no lock, no opening, except a narrow slit in the door’s center, now closed on the inside with a plate of metal, and a small signal button beside the frame.

No password had been demanded of the Agent as yet, but here was a barrier just as dangerous. In such a criminal group, each member surely would have his own signal, and “X” did not know Lorenzo Courtney’s password.

Yet he did not stand in uncertainty even for a moment. It was the Secret Agent’s way to act quickly, play hunches, flirt with Death itself. Firmly with no tremor in it, his finger pressed the circular eye in the button’s center and stayed there.

Chapter XIV

FOR a full second he held the button down, then removed his finger and fished in his pocket for a cigarette. If any bell had sounded inside he had not heard it, and he couldn’t risk the use of his amplifier now. His own flash beam had revealed a small electric bulb in the roof of the passageway’s end. Any instant that slit in the center of the door might open, and if it did, and he had his amplifier, he would be caught red-handed.

The cigarette he lighted wasn’t in answer to a nervous craving for nicotine. Neither was it an act of bravado. It was done deliberately to create a certain impression which he wished to give. The cigarette was one of Courtney’s own, cork-tipped, expensive. The Agent let it hang loosely from his lips, swayed on his toes, and hummed beneath his breath as he waited.

Almost a minute passed, and then the bulb over his head and the slit before him glimmered at the same instant. One slid back. The other lighted up with a startling click. But the Agent did not jump.

Still swaying on his toes, his cigarette lax in his mouth, Agent “X” faced the mysterious slit and smiled. He smiled — perhaps into the very face of Death.

For there was no further sound from the opened slit, no visible sign of life or movement. The chamber behind it was obviously black. The light overhead had been so arranged as not to fall into it. Yet “X” knew for a certainty that a human eye was there, an eye hidden, yet scrutinizing him with grim intensity. He sensed with intuitive awareness that he was not approved of.

At least another ten seconds passed, then a sepulchral voice spoke:

“Lorenzo Courtney!”

“Right!” The Agent put the same aplomb into his answer as was expressed by his teetering attitude, and the drooping cigarette. He squinted one eye to shut curling smoke out, said: “What’s the idea of keeping a fellow waiting?”

There had been a sinister harshness in the words of the unseen watcher; the harshness of the same voice that “X” remembered hearing in Craig Banton’s office during the fall of the uncanny dark. His one answer was like an insult, or a defiance hurled into the teeth of doom. But it brought the retort he had expected.

“Lorenzo Courtney, why did you not give the signal?”

The Agent’s coolness in the face of this demand was incredible — as fine a bit of acting as he had ever done in his life. He shifted his cigarette, removed it lazily from his mouth, flicked ashes to the floor of the passage.

“You won’t believe it, old man! But — the fact is — I’ve forgotten it!”

The Agent gave an amused titter, and drew a hand across his mouth. His accent had perfectly duplicated the British twang of Lorenzo Courtney. He continued the same suave tones, adding a slight thickness.

“Sorry! You’ll be wanting to use your damned whips on me next. But I was called to the club this evening for a few cocktails — and—” The Agent tittered again. “Frankly this mumbo-jumbo gets on my nerves at times. You ought to thank me for finding my way in.”

A single word came from behind the metal door: “Fool!”

A second passed, while the Agent still waited, hiding the breathless uneasiness he felt. He had thrown one of the strangest and most daringly simple bluffs of his life. Told a member of a hideously vicious gang that he had forgotten a signal which he had never known. Would it, could it possibly work? The Secret Agent had rolled his dice again.

And it appeared that he had won, for abruptly the door moved back. An arm reached out, yanked him angrily inside. A harsh voice spoke in his ear.

“Once perhaps you can get away with this, Courtney. But the Chairman would never allow it a second time. That would mean death! You took the pledge like the rest of us. You are under oath! I shall be forced to tell the Chairman of your conduct.”

The “Chairman.” Agent “X’s” thoughts raced. A moment later he almost started in spite of his iron self-control. For lights blazed above his head. He got a glimpse of his surroundings, and saw that he was in no damp passage or dusty cellar now. He was in a small corridor lined with white marble tiling, and at either end a neat door showed.

THE man standing before him, the man who had questioned him and let him in, was glaring at him now. Glaring through the eyeholes of a silk mask such as “X” had found in the chair in Courtney’s apartment and now carried in his pocket. The mask hid the man’s entire face. But a thrill passed through the Agent. For in that angular frame, that horselike head with its high, narrow forehead, those hunched shoulders, “X” believed he recognized another member of a now defunct banking firm, one Victor Blass, who had had a serious run-in with both the State insurance department and Norman Coe over the legality of guaranteed second mortgages on worthless property. Blass had been a wily scoundrel who had escaped the law. And now apparently he had joined forces with outright criminals. More than that, he was apparently in second command to the mysterious Chairman himself.

The Agent’s excited speculation made him appear to be in a daze.

“Put on your mask, fool!” said Blass. “You shouldn’t have come in without it any more than you should have forgotten the signal. Hurry! The others are ready. It is nearly time for the Chairman to come.”

“X” quickly adjusted the black silk mask of Lorenzo Courtney’s over his head, and Blass gave him a shove toward the door at the farthest end of the corridor.

Agent “X” opened the door and walked into a room that amazed him even more than the marbled entryway had done. For here was a carpeted chamber, with a polished desk, upholstered chairs and ornate electrical fixtures in it. The chairs were ranged around the floor, all facing in one direction, and ten men sat in them.

The group of black-shrouded faces under the glaring lights was weirdly incongruous. Their silence and preoccupied attitudes were strangely sinister. A few turned to stare at “X” as he took his place in a vacant chair. The rest held their gaze straight ahead. At the very end of the room a fine meshed, metal grille rose from floor to ceiling. Behind this was a single chair with a desk beside it. It was toward this desk and chair that the masked men were looking.

Agent “X” waited for the mysterious Chairman to arrive. His pulses were throbbing. It was obvious that this night he was going to see the body at least of the sinister being whose brains were responsible for the activities of the devil-dark gang. The man’s face would be hidden, but his movements, his mannerisms, might give the Agent some clue to his identity.

As the seconds passed “X” glanced at some of the still figures about him. He thought he recognized the bullet-headed, heavy-set form of Chauncey Doeg, the man he had followed here. Doeg, like the others, was awaiting the arrival of the Chairman.

Then abruptly Agent “X” tensed in his chair. The fingers of his right hand pressed involuntarily against its wooden edge. For a change seemed to have come over the room. The bulbs overhead seemed suddenly dimmer. There was an odd humming sound in the air that brought back vivid memories. Light moved before his eyes for a moment. He seemed to hear the terrified shrieks and curses of frenzied men and women in his ears.

THE lights grew dimmer, dimmer. The masked figures around him took on the appearance of weirdly, distorted ghouls, of beings from some unthinkable nightmare. Then they disappeared entirely, and blackness, utter and complete, enveloped the strange room.

“X” was not deluded. He knew that the lights above him had not gone out. He knew that it would be useless to wink his own flashlight on. For this was the same uncanny darkness that had descended on the bank; the same under which innocent people had been scourged brutally with whips that they might not interfere with the looting of the vault.

There were no cries or gasps around “X” now. The masked men evidently expected this to happen, were prepared. There was stillness in the room, until a slight, metallic scrape sounded from behind the grille. Then the faint scrape of a chair, then a voice.

“Greetings! I see you are all here! The meeting is about to begin.”

Agent “X” knew that voice. Its muffled, disguised tones had spoken to him over the telephone in Courtney’s apartment, given him his instructions to come. But it was distorted beyond recognition of the man from whose lips it came. And its words seemed a mockery of his purpose in coming. For it had said: “I see you are all here.”

That meant one thing. This man, this sinister Chairman, whose arrival had been awaited so tensely, wore a mask unlike the others in that room — a mask such as all the raiders on the bank had worn, and which enabled him to see his board of directors now. It meant, beyond a shadow of doubt in the Agent’s mind, that the directors did not know the identity of the Chairman who guided them.

The muffled voice of the unseen man behind the grille continued.

“Today, gentlemen, we have witnessed the complete success of our plans. The method, given a preliminary test a week ago, and which I outlined to you all last night, has proven itself more than adequate. You have read the papers this afternoon. You have seen how our little venture baffled the public and the police. I say ‘little,’ because what we did today is as nothing compared to what we shall do.

“Already our investment has paid a hundred per cent profit. There were two million in cash and negotiable securities in the Guardian Bank. Each of you shall receive his share. Dollar for dollar for the time spent, this is greater profit than any of you ever made in the heyday of your public careers. But the future, not the present, is what we must look to. The future, when we shall all be multimillionaires — able to do what we want, buy what we want — and wield the power that is the rightful heritage of brainy men.”

There was a gloating, confident note in the muffled voice. The hidden Chairman of this unholy meeting of criminals was talking as though he were at the head of some successful and legitimate enterprise. But brutal harshness crept into his tone as he continued.

“Discipline! As I said to you last night, that is the backbone of our organized power. We must have discipline if we are to get the maximum return from our investment. And because I realize the necessity of this perhaps more than any of you, I have given certain commands that some of you may think harsh. I have said that punishment even to death, awaits any man among you who does not submit to the majority will. I have ordered each of you to check up on the conduct of his neighbor, for in spite of the masks you now wear, most of you are known to one another. That none of you know who I am is an asset to you all, for in it lies unity and power. If it becomes necessary to impose a death sentence on one of you, I personally shall take pains to see that it is carried out.”

Chorused growls of approval greeted these sinister words. Then a harshly bitter voice spoke in the darkness a few chairs away from Agent “X.”

“Death!” the voice said savagely. “Shouldn’t we, Mr. Chairman, extend that penalty beyond our own membership to those who are and have been our enemies? There are several persons I have in mind; but one especially who exposed and helped to ruin many of us during our banking days. I refer to Norman Coe with his prying citizens committee behind him. Because of his officious meddling into my affairs I even served a prison sentence.

THE Agent guessed then that this was Chauncey Doeg speaking, still bitter that the law, through Coe’s efforts, had punished him for his shady financial dealings. The voice of the Chairman gave answer.

“You are right, my friend. There are many enemies we must and shall settle with in time. But at the moment personal revenge must wait on more important matters. And meanwhile, gentlemen, for minor breaches of discipline within your own ranks, you have the whips! The whips! You saw how well they worked on the people in the bank today. You saw how the girl we were forced to interrogate before the raid, even though she was stubborn to the point of sheer stupidity, eventually submitted under the lash.

“And I do not doubt that your whips will be sufficient to enforce discipline among you under all normal circumstances. In case the whipping of a member becomes necessary, I have worked out a plan which will remove the element of ill-feeling. I shall provide eleven of you with the helmets you wore today, while the member to be punished will wear only such a mask as you have on. He will not know who among you is whipping him.

“And now we come to our immediate future. I have looked over the field, gathered data for our next venture. There were several promising possibilities. It was merely a matter of selection. That I have made. We have successfully looted two banks. We have proved that our method has no limits. To show that we can operate with equal success over a larger area I have chosen a department store this time. That of S. Carleton Co.”

The Agent’s body tensed. A chill of horror crept up his spine. This criminal, this unseen Chairman, was deliberately, calmly, plotting a crime which, if carried out unimpeded, might bring death and injury to thousands. For the fearful, blinding darkness would cause a worse panic in the big store than it had outside the bank. Yet the Chairman’s voice continued:

“To insure that the cashier’s safe will not be empty we shall change our time from noon to four o’clock. The date is tomorrow. We shall meet and the helmets will be distributed among you in the same manner as they were today. And now, gentlemen, are there any more suggestions you wish to make, or breaks of discipline to be reported?”

A few seconds of silence followed in the uncanny gloom of the room; then a chair creaked and the voice of Victor Blass sounded. It was low, nervous, as though the man were half afraid to speak, yet more afraid not to.

“I have a report to make, Mr. Chairman,” he said. “It is my duty to complain against a member. I have taken the pledge like the others, and you have seen fit to make me responsible for their conduct. Therefore I must speak.”

“These explanations are unnecessary,” said the cold voice behind the grille. “Who is the member you wish to complain of?”

“Lorenzo Courtney, Mr. Chairman.”

Chapter XV

THE Secret Agent sat rigid and waiting in his chair. The harshly precise voice of the invisible leader behind the grille droned on:

“Lorenzo Courtney! Before I hear the charge against you there is a certain matter I must ask you to report on. Earlier this evening you were commissioned by a friend of our organization to take charge of and question one suspected of being a possible dangerous enemy. I refer to the newspaper man, Sid Granville. What have you to say about this?”

Prickles of tension coursed up the Secret Agent’s spine. He could almost feel those unseen eyes back of the metal grille boring into his own. A faint rustle of clothing and creak of chairs in the gloom around him, told that the other members of the meeting were straining to hear his answer. And on that answer might depend the success or failure of his desperate, daring step in coming here. He rolled his shoulders, shrugged, and kept his voice nonchalant.

“I did my best, Mr. Chairman, but the man wouldn’t wake up. Mrs. — er — our friend gave him too strong a drink. I had to leave for this meeting before his answers made sense.”

“So — and where is this man now?”

“At my apartment. I’m still holding him.”

“You have taken every precaution, of course, to see that he does not escape?”

The Secret Agent let a moment pass before he answered. Then, with deliberate craft, he put a quaver of uncertainty into his voice. “Yes, sir — I think — that is, I’m sure he is safe.”

Victor Blass spoke with sudden excitement. “Pardon me, Mr. Chairman, but you should know before this goes farther that Lorenzo Courtney was drunk when he arrived tonight.”

“Drunk!” The word came out of the darkness explosively. “You mean he came to this meeting drunk?”

“Yes.” There was hesitancy in Blass’s voice now. “And if I hadn’t known him — hadn’t recognized him at once — I wouldn’t have admitted him. He couldn’t remember his signal, sir, and he had neglected to put on his mask.”

A stifled curse sounded behind the grille. A momentary silence followed it. Then the Chairman spoke as calmly, as precisely as before; but with a touch of sardonic mockery in his tone.

“Courtney is at fault — wholly and unquestionably. Men engaged in such an enterprise as ours cannot, must not, touch liquor. But shall we say, Victor Blass, that your own conduct has been entirely wise and praiseworthy — a perfect model for the other members to follow?”

A gasp sounded from the direction of a chair in the rear of the seated group. The relentless voice of the Chairman, continued:

“You had your orders not to let any member into this meeting until he gave his signal. Do orders mean nothing to you?”

Stark terror, proving the power that this leader had over his men, trembled in Blass’s reply. The brutal confidence he had displayed during the bank raid was gone.

“I–I was afraid to turn him away in his condition. I weighed the factors — and reached a decision to meet the emergency. I — appeal to you, Mr. Chairman.”

The Chairman’s laugh held no mirth, no mercy. “I shall give the matter thought, and meanwhile—”

“Meanwhile, Mr. Chairman, if Courtney was responsible for a prisoner, something ought to be done. He is in no state—”

“I am coming to that, Blass! Two of you, Doeg and LaFarge, will accompany Courtney back to his apartment at once. If Granville is still there, Courtney will be punished for his misconduct with a whipping only. If Granville isn’t there — I shall consider that Courtney has committed a major breach of discipline and is of no further use to this organization. In that case — I shall decree his death!”

There was another silence in the room, during which there came again the scrape of a chair and a faint click. Then, weirdly, mysteriously, the chamber began to grow light. The masked faces of the men around “X” appeared slowly as out of a haze.

Instantly his eyes swiveled toward the grille at the end of the room. But the chair was empty now. The sinister Chairman had withdrawn. There was some doorway close to that desk through which he had passed. It was he who controlled the falling and rising of the darkness.

TWO masked figures in the group arose at once: Doeg and LaFarge, the members delegated to go with “X” to Courtney’s apartment. “X” stood up also, walked toward the door into the corridor through which he had come. Victor Blass opened the metal door with its slitted peephole, letting them into the outer passage. The two who were now “X’s” guards removed their masks, and he did likewise.

They stared at him with open hostility, pushed him roughly ahead of them along the passage, and Chauncey Doeg, Courtney’s supposed friend, spoke:

“You’ve been a damn fool, Lorenzo! You deserve anything you get! Your conduct reflects on us all. From now on you’d better watch your step. Understand? If you don’t — we know what the Chairman would expect!”

Doeg flipped open his coat, exposing the black butt of an automatic worn in an armpit holster. The other man, LaFarge, laughed mirthlessly and nodded. “X” knew that these two wouldn’t hesitate to shoot him. The disapproval of the Chairman, the sentence of a brutal beating already imposed upon him, gave them little respect for his life. Their own selfish interests swept friendship aside. There could be no loyalty among criminals, except that inspired by fear.

But the Agent did not intend to let these two men accompany him to Courtney’s apartment. The mythical Sid Granville wasn’t there. Ironically, the man who had impersonated Granville was now before them and they didn’t know it.

“X” wasn’t interested in either Doeg or LaFarge now. They were only cogs in the amazing crime organization that the mysterious Chairman had built up. Even Blass had proved himself to be a mere subordinate. The Chairman shared his secrets with no one. Unseen, unknown, he controlled the darkness and gave out the helmets which offset it. It was he who was the guiding genius of the devil-dark group. And his sinister orders would start the pillaging of S. Carleton Company’s great store tomorrow.

The Agent moved like lightning, just as they reached the shadows surrounding the spot where LaFarge had parked his car. Before Doeg was able to draw his automatic, the Agent’s fist cracked sharply against his chin. The Agent whirled, struck again, and the second blow, with the impact of a trained boxer’s behind it, connected with LaFarge’s jaw.

Both men dropped senseless to the pavement while Secret Agent “X” turned and sped away. He ran two blocks, turned a corner, and leaped into his own parked coupé. In a moment he was speeding off into the darkness.

TEN minutes later Agent “X” turned into the mouth of the mews where Vivian de Graf dwelt. The pink stucco building which housed her ground-floor apartment was in the center of the block. A faint light seeped around the edges of drawn shades. In spite of the late hour the woman was still up.

The Agent, still in the guise of Courtney, pressed the bell button.

None of his inward excitement showed on his disguised face as he waited for his ring to be answered. The smell of Courtney’s whiskey was still on his breath. He had paused a few moments before entering the mews to bring his impersonator’s art into play. He had added a few deft touches of discoloration to the plastic material on his face. His lips were paler. There were circles under his eyes. The eyes themselves were bloodshot.

He teetered unsteadily and let his lids and his lips droop in an unpleasant smile as the door before him opened.

Vivian de Graf, clad in a becoming pair of blue lounging pajamas, stood in the threshold. Highlights gleamed on her dark hair and on the clinging silk that covered her. They emphasized the pliant grace of her figure. Her complexion was freshly made up as though she expected a guest. Her scarlet lips were startlingly defined, her eyelashes heavy with mascara. Never had she looked more alluring — never more exotically beautiful.

But her features froze as she saw the man who came as Courtney. She did not move aside. Her voice was hard.

“What is it, Lorenzo? What do you want — coming here at this hour?”

The Agent gave a tipsy salute. He leered at her knowingly. “Jus’ wanna have a li’l’ talk with you, Vivian. Jus’ a li’l’ talk.”

“You’ve been drinking,” she said scornfully. “I can’t see you now.”

She tried to shut the door in his face; but Agent “X” thrust out his foot.

“Bad girl, Vivian! Treat a frien’ like that!”

He pushed her aside, swaggered into the apartment where the faint, but all-pervading scent of the saffron orchids lay. Vivian de Graf was beside him instantly, panting in anger, her chin outthrust. Her beauty now was like the sinister grace of a lioness about to spring, with rending claws hidden beneath sleek fur.

“Get out!” she cried huskily. “You — drunken fool! What makes you imagine I want to see you?”

“Nobody — said — you — did,” the Agent replied slowly. “But — I wanna see you.” He took off his hat, dropped it into a chair, fingered for a cigarette. Vivian de Graf eyed him keenly. A sudden look of uneasiness crept into her gaze.

“How long have you been like this? What did you do with Granville? Where is he now?”

The Agent held up a protesting hand. “Not — so many questions at once, Vivian, m’dear! One at a time, please.”

“Where is Granville now?”

Agent “X” lighted his cigarette, let smoke dribble from his lips before he answered. Eyes half closed, drunken appearing, he watched her growing uneasiness.

“That,” he said haltingly, “is what I wanna talk to you about. He — got away.”

Anger became fury in the woman’s face. Her hands clenched at her sides as she stepped close. Her sleekly clad body was taut in every rippling muscle.

“Fool! Fool!” she said again. “I asked you to be careful! I thought I could trust you — that much!”

“Sorry,” said the Agent. “But I’m the one you wanna worry about. I’m in bed with the boss — an’ you — gotta help me!”

“Exactly what do you mean?”

“X” gave a humorless laugh. He waved a finger close to her face. “There was a meeting tonight, an’ the boss wanted to know what I’d found out about Granville. I stalled. I couldn’t tell him the bird had flown. I said he was at my apartment. Then the Chairman, the boss, sent two fellows back with me to find him. The boss said that if Granville wasn’t there — I’d — be killed. So I shook them — and came here.”

THE woman’s expression showed that she understood all he had said. “Well — what do you expect me to do?” she asked.

Agent “X” drew himself up with the exaggerated dignity of a drunken man. He stared at her solemnly, accusingly. “You got me into this! You — wished that bird on me! Now — you gotta make it right with the boss. You know him!”

She didn’t deny it. She gave a scornful laugh. “It’s your own funeral. If you hadn’t got drunk—”

The telephone sounded suddenly, and Vivian de Graf turned. The first flare-up of her anger had passed. She was poised now, coldly scornful. “X” watched her lift the receiver. Saw her listen and glance his way. He couldn’t hear the voice that spoke at the other end of the wire; but the meaning of her answer was plain.

“He’s here now. You’d better have them come — at once!”

There was a note of cruelty in her speech. She clicked up the receiver and faced him, smiling thinly with red lips.

“It’s too bad, Lorenzo! You might have gone far — if you hadn’t been a fool!”

The Agent let panic come into his voice. “You told him I was here! You — They’ll kill me!”

Vivian de Graf threw back her head and laughed, white teeth gleaming, supple body relaxed. The thought of his death seemed to amuse her.

“You will get only what you deserve,” she said.

The Agent’s manner changed as though fear had cleared the fumes from his befuddled brain. He drew his face into a scowl; clenched his fist. “No — I won’t wait to be murdered. And — you’ll be sorry for this!”

She did just what he expected then. Her white hand streaked to a drawer in the table at her side. It came out clutching a gun which she centered on his vest.

“Stand still, Lorenzo, or I shall save them the trouble of killing you — by doing it myself.”

Her steady hand, her merciless eyes showed that she meant it. A cruel smile still curved her red lips.

She was standing on a rug. The other end of it was close to the Agent’s feet. There was polished flooring beneath. Suddenly his heel moved forward and jerked back on the fabric. It was done so quickly, so deftly, that Vivian de Graf made a clutch at the table to save herself from falling. In that instant, before she could swing the gun muzzle toward him again. Agent “X” leaped forward and disarmed her.

Furious, white-faced, she stood before him as the Agent centered the weapon on her heart. He was still playing the part of Lorenzo Courtney, but in another, more masterful role.

“Now,” he said, “call the boss! Tell him that if he sends anyone to get me — you’ll die first.”

Tense seconds went by while the woman weighed his words. He had no intention of making good his threat; but she didn’t know it. It was made only to force her to reveal the mysterious Chairman’s telephone number. Vivian de Graf shrugged and said in a flat voice:

“You win, Lorenzo. You are smarter than I thought.”

She turned toward the phone, reached out resignedly to pick it up, and as she did so Agent “X” caught his breath. For a change was suddenly apparent in the room. The walls were growing darker, the electric bulbs overhead dimmer, and there was a buzzing sound in the Agent’s brain, while streaks of light danced before his eyes.

Vivian de Graf’s white face was becoming blurred. He saw her drop her hand from the phone, saw her turn toward him, but he couldn’t see her features clearly enough to get her expression. Yet he knew what was happening, knew that the weird, blinding blackness of the devil-dark gang was descending in the room.

Chapter XVI

THE Secret Agent stood frozen. He wasn’t afraid. He was amazed. This upset all his plans. It baffled him utterly. He crouched and moved crabwise toward the wall. He fumbled along it toward the door, listened for steps in the street outside. The room was completely black now. There was no sound from Vivian de Graf. He couldn’t even hear her breathing. He put his hand on the doorknob to turn it, knowing there might be men with guns waiting outside. But he was ready to take a chance.

Then he heard a noise which came from directly opposite across the big room. There were French windows there. His roving eyes had noticed them earlier. The noise sounded like one of the windows being pushed open by a stealthy hand. The killers were evidently coming to get him that way. They had the front guarded, the place surrounded, and all ways of escape cut off.

But his reasoning was upset the next instant. For Vivian de Graf spoke in the darkness, mortal terror seeming to constrict her throat.

“Who’s there? Who is it? Oh, my God—”

The person by the window didn’t answer with words. His reply was more abrupt, more terrible than any speech could have been. It was a shot in the utter gloom of the room, a shot that seemed to find a mark, for Vivian de Graf gave a piercing, pain-racked cry.

The Secret Agent waited aghast, trying to make sense out of this seemingly senseless thing. He heard the woman’s cry repeated, heard it choke in her throat as though Death’s fingers were already pressing there, heard the table go over as though she had clutched at it. Then came the unmistakable thud of a falling body. Even the rug could not muffle it entirely. It only made the sound more gruesome — like rock being thrown on a coffin lid.

The thud was followed by a moment’s silence. Agent “X” thought the unseen assassin was taking aim at him. But instead there came a frenzied curse in the darkness and the crash of a falling vase. It was not accidental, for swift footsteps moved across the floor, then another vase was shattered, and still another.

A madman seemed to have entered the chamber under cover of that blinding dark. He appeared to be preoccupied in some inexplicable work of destruction all his own. For “X” could hear him crushing the pieces of broken pottery underfoot, stamping among them, breathing in great gasps.

Every muscle tense, the Agent suddenly leaped forward. He could learn nothing by crouching in the dark. His curiosity was aroused to the point of risking death.

A man snarled. “X’s” plunging body struck yielding flesh. Something crashed against his shoulder, and a second shot sounded deafeningly in his ear. But no bullet struck him, and his fingers closed over a human arm.

He dug in, swung his left arm around the man he had gripped, and knocked the mysterious visitor off his feet. In a tumbling, crashing heap, they went down together among the pieces of splintered vase.

Deliberately then the Agent reached forward to feel the man’s head, expecting to encounter one of the round helmets such as he had touched in the bank. But this man, though he could obviously see in the dark, was not wearing the same sort of helmet. His was softer, more wrinkled, fitted with a cord around his thin neck. The Agent tried to tear it loose, and the man seemed to go insane.

He was bony, lean almost to the point of emaciation, but possessed with the superhuman strength that some inward fire of emotion gave him. He fought like a madman, biting, clawing, kicking.

The Agent drove a knuckled fist against his jaw; but the pliable helmet deadened the blow. The other’s head snapped back, but he did not pass out. And, able to see, when “X” couldn’t, he succeeded in bringing the muzzle of his gun down on the Agent’s wrist with paralyzing force. “X” felt his fingers loosening, felt the muscles of his arm where the blow had fallen going limp. He levered his other arm forward, grabbed the gun, and jerked it free. But as he did so, the lean man rolled away across the floor.

“X” heard the window grate again. He swung the gun toward it, started to pump the trigger, but held his fire. His quick mind was already checking over impressions. Something had clicked in his memory.

THE window slammed back as a man leaped out. A shoe scraped against stone in the darkness outside, no blacker than that in the room. But in another moment, as “X” picked his way gingerly over the floor, nursing his bruised arm, lightness began to come. Not through the window, but from the bulbs overhead. The darkness was lifting again, as mysteriously as it had fallen — and it lifted on a room of death.

For Vivian de Graf lay sprawled on the rug by the overturned table. Crimson was spread over her blue pajama coat; crimson, just under the heart, darkening the glisten of the silken fabric.

The Agent crossed to her in one swift stride. He bent down and pressed his fingers on her outflung wrist. But there was no pulse flutter. That single shot, fired in the dark, had done its work well. Vivian de Graf was dead. Even so, she was beautiful, red lips a splash of color across the whiteness of her face, eyes closed as if in sleep.

But the Agent did not pause to stare. Hers was not the only beauty that had been stricken in that room. The frenzied slayer’s passion had not stopped at taking human life. Among the splintered pieces of pottery lay the stems and petals of a score of saffron orchids. The Agent’s eyes darted along the floor. Three vases filled with the flowers had been smashed. The spotted blossoms had been trampled on, their destruction as deliberate as the woman’s death, and done in the same murderous fury.

A single orchid, kicked accidentally under a chair, had escaped. The Agent picked it up, stared curiously. The poisonously spotted petals curled like living things. The flower’s dark center seemed an accusing eye.

He took an envelope from his pocket, dropped the flower in and slipped it in his coat. Then he glanced at the woman again, and noticed for the first time that the rug at her feet had been kicked away by her silken leg as she fell. Under the rug’s edge, close to the table, was a small metallic plate set just above the level of the floor. Some sort of electric switch — and the Agent’s eyes narrowed instantly.

He strode to it, placed his foot on the thing tentatively, and pressed down. Almost at once the lights above his head grew dimmer, and there was that strange buzzing in his ears. He took his foot off and the sensation stopped. He understood now. This was how the darkness had been made.

There was a hidden mechanism to produce it somewhere in the room. Wires led from it to this floor switch. Vivian de Graf had tricked him when she pretended to reach for the phone. She had stepped on the switch beneath the rug, started the mechanism in motion. The shot that found her heart and made her fall, had released her weight from the plate and automatically turned the mechanism off.

Agent “X” began a hurried search for the thing that could bring darkness blacker than night to human eyes. It would be hidden, but it must be somewhere in this chamber. He bent above the floor switch again, intent on seeing which way the wires beneath it led.

But abruptly his search ceased. For a car whined in the night outside and came to a purring halt. Then voices muttered and footsteps sounded close to the vestibule door. The bell of Vivian de Graf’s apartment made a silver tinkle in the kitchenette, a moment passed, and a key grated in the lock.

The Agent leaped from his kneeling position over the switch. He must not be found here, whether by bandit members or police. There was much to be done, a fresh lead he believed he could follow, a new line of action to pursue. He flung toward the window soundlessly on his rubber-soled shoes. He opened a side of the casement with quick care, stepped through into the darkness of a court as the unseen assassin had done. A moment more and the shadows of the night had swallowed him completely.

HE emerged from shadow fifteen minutes later to cross the rear yard of an ancient brownstone house. He had climbed fences, come through other yards to get here. Light from a single large window in the house before him cast dim illumination on the stone flagging at his feet. The Agent looked like a flitting ghost as he moved forward. He was still disguised, as Lorenzo Courtney. His eyes were raised to the window above. There was a look of intense concentration on his face.

For a man’s head moved across the window, turned and moved again. Some one was pacing restlessly in the lighted room, some one who could not keep still, though the hour was late and the rest of the house was dark.

The Agent slipped through an alley at the building’s side. He passed into the quiet street. Here he turned and silently mounted a flight of steps. There was a door before him and a bell button to press, but he did not touch the latter. His set of oddly shaped chromium tools came out. Under the pencil-thin beam of a tiny electric flash he probed in the keyhole.

So quickly and silently that the pacing man was unaware. Agent “X” entered the hallway of the house. He moved directly toward the rear, toward that single lighted room. His eyes were gleaming, his whole body was alert, and in his right hand was the gun he had taken from the mysterious killer who had come to Vivian de Graf’s. But as he pushed the door before him softly open, he held the weapon behind him.

The man in the room was thin, stoop-shouldered, with the look of a scholar about him. His gaunt face had a sickly, ghastly pallor. When he saw what appeared to be Lorenzo Courtney standing specterlike in the door he gasped and crouched back.

A thin smile curved the Agent’s lips. He was watching the other’s actions intently. And he had learned from them what he wanted to know. “I see that you recognize me, de Graf!”

The man who had been pacing the lighted laboratory in the old-fashioned house, leaned against a chair and passed a shaking hand across his face. He looked ten years older than when the Agent had last seen him. He raised haggard eyes, stared at the Agent dully.

“I don’t know what you mean,” he said. “I don’t know who you are. Get out of here — before I call the police.”

The Agent’s answer came relentlessly. “Emil de Graf, you’re lying. I recognized you when we fought — even though I couldn’t see you! And this is your gun.”

He thrust the weapon into sight, saw the scientist start guiltily.

“It’s the gun you killed your wife with. You are a murderer, de Graf — the murderer of your own wife!”

The face of de Graf had become grayer still. He was swaying on his feet, staring dazedly at his accuser, and Agent “X” continued:

“I know your motive. You were jealous, de Graf — insanely jealous. Behind that pretended calm of yours, behind that tolerance you professed, you were angry at your wife’s interest in other men. That’s why you killed her!”

Emil de Graf clenched his fists. “I should have killed you, too, fool that I was!” he cried. Then added hoarsely: “For God’s sake who are you? What do you want?”

The Agent’s answer was to walk slowly forward, the gun pointed at de Graf. His stare had the inexorable quality of Fate itself.

“Then you admit it,” he said quietly. “You admit you killed your wife!”

The scientist cringed, backed away. “No! No!” he gasped. “I admit nothing. You can’t have me arrested. They can’t send me to the chair. There’s no proof—” He broke off, breathing heavily, and stood as though transfixed by the Agent’s level, accusing stare.

“You are a scientist, de Graf,” “X” said quietly. “You know that, given certain facts, you can discover the truth about natural phenomena. It is the same for human actions. I know that you were jealous of your wife. I know you tried once to throw acid in her face, so that other men would not find her beautiful. I know that when your attempt to mar her beauty failed, you became desperate to the point of madness. Can you deny that?” The Agent stepped closer to de Graf. “I know that you came to Vivian de Graf’s apartment an hour ago. I fought with you in the darkness. Your wife lies dead in that room now, shot through the heart. Here is the gun from which the shot was fired. Your gun, de Graf! You killed your wife!”

Clammy moisture beaded de Graf’s forehead. His shoulders drooped. He seemed on the verge of collapse as he nodded slowly, unable to face the Agent’s accusing eyes.

“Yes—” he said dully. “Yes — I shot her, as you say.” The smoldering fires of passion flamed in his eyes. “But she gave me cause! She has tricked me, humiliated me, hurt my pride for years. She was a poor girl when I married her. She looked up to me as a great scientific worker. I took her out of the impoverished life she had known. We traveled, met interesting people. Then she got a taste for luxury. Men flattered her. It went to her head. She forgot all I’d done for her, forgot the vows she’d made. She called it being modern. When I objected she threatened to leave me. To keep her, I had to agree to her ways. She dragged my name through the public press, created scandals. She even took up with — a criminal.”

The Agent’s eyes flashed. He leaned forward. “This criminal, de Graf, who was he?”

“I don’t know his name. But she dared brag to me — boasted that she’d grown tired of Roswell Sully, and had found some one who suited her better. A criminal who, she said, was a greater scientist than I. She was a child about such things. I didn’t believe her until I visited her one night at her apartment, and she turned the darkness on me from a mechanism this man had given her. She laughed at me under cover of it, and said she was afraid of me no longer — and would leave me for good—” He broke off, trembling.

“And so you set to work to find out what the darkness was,” Secret Agent “X” prompted, “and made a helmet to combat it. You learned that it wasn’t darkness at all, but a force that blinded human eyes.”

“Yes,” the scientist nodded eagerly. “I had to show her I was as good a man as that lover of hers — even though I couldn’t shower her with orchids. And I–I—”

“You succeeded — and you killed her.”

De Graf nodded. “Yes, I succeeded, and now that you know the truth you’re going to turn me over to the law. You are a detective, of course.”

The Agent shook his head. “No. Hunting criminals is my work — just as yours is science. But I’m not interested in crimes such as yours — crimes of passion.”

“Then why did you come here?” de Graf snarled. “What do you want?”

“Only one thing,” the Agent said sternly. “The helmet — the one you used tonight. Give me that and the law shall never hear from my lips that you are the murderer of your wife.”

Chapter XVII

THE following afternoon Secret Agent “X” stood near the marble and chromium main entrance of S. Carleton Company. Shabby clothing covered the powerful, athletic lines of his body. Nondescript features disguised his face. His manner was dejected. The fiery alertness of his eyes was hidden by the wilted brim of an ancient felt hat.

He attracted little attention from the throngs surging in and out of the city’s largest department store. Once an old lady, touched by his appearance of abject want, slipped a dime into his ungloved hand. The Agent, living up to his role of down-and-outer, acted humbly grateful as he pocketed the coin.

Inside the big store, three thousand shoppers, unaware that the hideous shadow of crime hovered just above their heads, crowded through the aisles, pushed into packed elevators, stood impatiently on escalators, jostled, talked and laughed. Scores of detectives, pretending to be shoppers also, mingled with them. These were picked men of the headquarters division, warned into utmost caution by strange orders they had received, and keeping their guns, blackjacks and bracelets carefully out of sight.

They had arrived from two o’clock on, singly and in pairs, converging on the store from many directions, entering unobtrusively through a dozen different entrances. And the Agent had smiled in grim satisfaction as he watched them come.

No one of the passing detectives gave his drooping, shabbily clad figure a second glance. They took him for what he appeared to be — merely a dejected member of the city’s army of unemployed. Yet it was he who was responsible for their coming there. It was he who had telephoned a startling message to the commissioner earlier in the day, giving the police head explicit directions.

Agent “X” had refused to tell his name. But his voice had carried the ring of absolute assurance, and he had made the police commissioner an amazing promise — so amazing, in fact, that though the commissioner was skeptical he dared not ignore what his nameless informant had said. And the steady but cautious arrival of detectives on the premises of S. Carleton Company proved that he had acted at once.

As Agent “X” stood in front of the store, a newspaper dropped by a careless shopper, slid by his feet. The Agent picked it up like a down-and-outer, grateful for any small favor that circumstance bestowed.

Lurid headlines screamed the news: “Society Beauty Murdered.” A picture of Vivian de Graf stared arrogantly from the page. The words beneath described the finding of her body in her exclusive mews apartment. They stated also that her husband, Emil de Graf, distinguished professor of physics at City University, had been found murdered in the brownstone house where he lived in another part of the city.

This did not surprise the Agent; though he read the story with interest. He had promised not to mention de Graf’s crime to the law, and he had kept his word. But the criminals with whom Vivian de Graf had cast her lot had taken swift vengeance, guessing apparently, just as “X” had, who her slayer was.

He turned the page over, saw one more news item which held his attention for a moment. This told of the finding of Lorenzo Courtney’s body on a park bench early that morning. A patrolling cop had made the discovery. Letters and a wallet in the dead man’s pocket had led to speedy identification. Financial worries were supposed to be the cause of the suicide.

The real motive was known only to Secret Agent “X,” the man responsible for the placing of the body on the bench in the dead of night. For that had been his answer to the unknown Chairman of the criminal group — an answer that would lull suspicion. And only he, outside of the criminals themselves, knew how closely these three events — the murders of Vivian and Emil de Graf and the suicide of Courtney — connected.

He dropped the paper, strolled to a corner of the big store where he could see in both directions. Casual as his manner seemed, excitement pulsed through his tautly alert body. The zero hour of four was almost at hand.

Down the block, a small electric truck with the name of the city lighting company on its sides rattled into view. It stopped beside the curb and a man in overalls emerged, carrying a pair of large, heavy pliers. He looked like a workman. Another man in overalls followed him, a coil of black wire slung over his arm. They lifted a manhole cover and descended below street level.

A minute or two passed, and both reappeared, drawing the length of wire from the hole in the street back to the parked truck.

The thing seemed commonplace. No one passing gave it a second glance. But the grim light of battle sprang into the Secret Agent’s eyes. Collar turned up, blowing on his hands like a bum trying to keep warm, he shuffled nearer the workmen and their truck.

From the corner of his eye he saw two other cars draw up on the same block. There was an air of casualness about the young men within them. They didn’t get out at once, but lighted cigarettes and shuffled through the pages of small books like salesmen going over territory lists.

THE Secret Agent looked quickly across the street toward a window where a clock giving U. S. Naval Observatory time was visible. He watched the minute hand crawl around its arc till it touched the exact hour of four. Then he glanced back at the parked truck again. One of the men, as the Agent stared, disappeared inside.

A moment passed, and the Agent stiffened. A sharp tingle shot along his nerves. It was getting dark now. A cloud seemed to have passed over the sun, a gloom like twilight was settling down. And in the Agent’s head was the strange buzzing that foretold the coming of synthetic night.

Grimly, tensely, he stepped into a doorway out of sight and drew a piece of rubberized fabric from a pocket. It was the helmet mask de Graf had given him the night before, the mask that represented hours of patient, secret research on the part of the murdered physicist.

The Agent knew now, had known for many hours, since the unfailing eye of Hobart’s movie camera had made its record, that the darkness had no external existence, but was in the eyes of human beings alone. It was a force, a ray probably, that temporarily paralyzed the optic nerve. No wonder that the darkness seemed more complete than any night. No wonder that criminals could work beneath it with impunity — criminals equipped with insulating helmets which made their own eyes impervious to the ray.

There was sweat on the Agent’s forehead as he adjusted the strange mask over his head. A great crime was about to take place — and the safety of thousands depended on him alone. The police were coming. Detectives were already in the store; but police and detectives would be helpless against the blinding dark. They would flounder as futilely as they had on other occasions when it had fallen. Whips would be plied by the raiders, men and women would stampede, horror would be repeated perhaps.

Yet to trap the criminals red-handed, to expose them for the fiends they were, “X” had been forced to wait until the darkness fell before he acted, forced to let the first fearful horror of the thing descend.

The mask of de Graf, fashioned of gum rubber impregnated with lead sulphide and the rare metal, thorium, had goggles of pressed mica and glass. It was almost a perfect insulator. Already the buzzing in the Agent’s brain had diminished, as the action of the invisible, nerve-paralyzing rays was lessened. The lights before his eyes had ceased to dance. The twilight grew brighter.

But pandemonium had arisen in the street, and the scene he saw before him was like a glimpse into some unearthly hell — a nightmare of horror that the Secret Agent was never to forget. On all sides people were floundering, pushing against each other. Their eyes, though blinded by the devilish ray, were wide with terror. The hoarse cries of men mingled with the piercing screams of women in a shrill tumult. Hysteria quivered like jagged lightning through the crowds.

The Agent turned his helmeted head toward the electric truck. The two workmen were carrying on their task quite calmly in the midst of mad confusion. How they could do this was plainly evident to “X” now. They, too, had helmets on their heads — helmets which proved their guilt as members of the devil-dark gang.

“X” SAW other helmeted figures slip from the two cars that had so quietly parked. Whips and canvas sacks were in these men’s hands. They pushed their way through the staggering, milling crowds toward the department store’s front. They entered as the Agent watched. He knew that others were entering through other doors that he could not see; knew that the raiders were gathering to do their work of looting. In a moment more, when the dark had so frightened the crowds inside that panic swept among them, those cruel, metal-tipped whips would begin to descend.

A second longer the Agent crouched in the doorway, looking both ways along the street. He hoped somewhere to see the directing genius of all this, the mysterious Chairman whose identity he did not know. But if he was here he was well hidden — hidden even from the Agent’s searching gaze.

Glancing back at the truck again, he saw one of the workmen strike out with a whip. A man and a girl had stumbled over the cable on the pavement, and were being lashed out of the way.

The whip curled around the girl’s body like a snake, its metal tip tearing at her dress. The workman drew it back, lashed again, ripping the clothing in great jagged seams, baring the white skin beneath. The girl screamed wildly, and ran headlong from the vicinity of the truck. The young man with her tried to follow, but stumbled against the vehicle instead, and a shower of stinging strokes sent him cowering back.

With breath hissing between clenched teeth, with fury lying hot against his heart, the Secret Agent fought his way through the seething mass of humanity about him. It was time for him to strike, time for him to make good his promise to the police.

People flung themselves against him, clawed at him blindly as he circled and made for the truck. He slipped like a ghost in that black gloom through crowds now almost mad with fear.

Feeling themselves secure, not knowing that anyone had guessed their secret, the men by the truck did not see the weirdly helmeted form until “X” was within twenty feet of them.

A startled cry came from behind one of the helmeted heads then. The man shouted something to his companion above the uproar. Both men stared. Then suddenly they dropped their whips, and automatics gleamed dully in their straining hands. Like weird monsters they crouched to fire.

Only rarely did the Secret Agent carry deadly weapons. But against this hideous band of whip-torturers who had killed women and robbed innocent children of their lives he had come armed. The weapon in his hand spoke quickly now. With the gun held close against his hip, not even taking aim along the sights, he fired twice, at the same instant that the others shot.

Bullets whistled close by his head, slapped against a building behind him. But the Agent had ducked the moment after he fired, and his own shots had found their mark. One of the helmeted men cried out and pitched forward. His hands dropped at his sides. Like a puppet with suddenly severed strings he collapsed. The other man staggered, his gun clattering to the street. He was not mortally hit like his companion, for he plunged to the back of the truck, his hand flew forward to a hidden switch, and an instant later a blast of blue and orange flame came from the truck’s interior.

The wounded man leaped back from the vehicle with a cry of pain. His plunging body struck the Agent. Both went down, and scorching heat funneled out from the burning truck, singeing their clothes. The wounded man groaned and went limp.

Agent “X” dropped his gun and pulled the man away from the hungry heat of the fire. For a moment he went dangerously close himself, trying to get a look inside the truck, and glimpse the mysterious mechanism. But it was hopeless. Some violently inflammable substance had obviously been planted to make the complete destruction of the mechanism possible in case of emergency. White-hot flames hissed and interlaced, as though a hundred blow torches had been fired at once. Glass tubes were popping in a series of miniature explosions. Lead connections were melting away. Metal was fusing into a bubbling, shapeless mass.

THE Agent backed away from the mystery truck and looked around the street. A change was already beginning to make itself apparent in those about him. The excited, terrified milling of the crowd was beginning to cease. Suddenly a man screamed and pointed toward the fire. There was a note of hysterical joy in his voice.

“Light! Light!” he shouted. “Light again — thank God!”

The fierce white-hot glare of the inflammable material planted in the car had broken through the blinding darkness of the Stygian night. Did that mean — As though in answer to the Agent’s unfinished thought others around began to shout:

“The sun! The sun is coming out again!”

With a grim smile on his lips, the Agent tore his helmet off and stuffed it in his pocket. It was true! His own eyes, unaffected previously by the strange rays, could see perfectly now without the glass goggles. The rays were no longer radiating. The mechanism in the truck had been put out of commission by the fire. The crowds in the street were slowly regaining their normal sight as temporarily paralyzed optic nerves began again to function.

And it was the Agent, by his swift attack, who had forced the raiders to destroy their own dark-producing device. The burning had been done, of course, as part of a prearranged plan, thought out by the Chairman, to prevent the secret of the blinding rays from falling into the hands of the law. Normally, before the effect of the rays wore off, the raiders would have time to escape — as they had done on two previous occasions. But here again the Secret Agent’s action had changed things.

For the helmeted raiders were now in the big store of S. Carleton Company, detectives guarded every exit, and neither of the two men in charge of the truck had been able to warn their companions what had happened.

Agent “X” turned and made his way quickly to the store. By the action of the people around them, the raiders had now learned that something was radically wrong with their plans. But for them it was too late. Their lashing, metal-tipped whips could beat blinding humans into cowering fear, but they were of little use against grim detectives, armed, and already partially able to see. The Agent watched the scene tensely. He had done his work well, given the guardians of the law more than an even break — and they were making good use of it.

When two of the helmeted raiders discarded their whips, drew guns and started to fire, they were met with a volley of bullets. But a fierce fight was raging by another exit. Four of the raiders had concentrated their frenzied attack to escape here. Two were grabbed by wounded detectives and made prisoners. Two others managed to break through.

Grimly the Secret Agent crouched with his gun in hand again. He fired as the helmeted running figures appeared, sent bullets smashing into the bandits’ legs, and saw them sprawl cursing and screaming to the sidewalk.

Inside the store, the terrific battle had been won. A dozen detectives lay dead and wounded on the main floor. Victims of the first slashing onslaught of the terrible whips cowered in whimpering terror against the walls and counters. But the raiders — those still alive — were in the hands of the police, guns pressed against their sides, steel handcuffs clamped over wrists.

Not a single member of the raiding gang had escaped. They had been caught red-handed with all their hideous paraphernalia — their cruel scourging whips tarnished with the blood of a hundred victims, their guns, canvas sacks to hold the loot, and their strange helmets.

Detectives, coldly angry at the death of some of their comrades, were jerking the helmets off the heads of their prisoners, smashing down with blackjacks and gun muzzles when open rebellion flared. And the raiders were a bruised and vicious group when their faces were finally bared to the gaping crowds. The Agent recognized a few; Doeg, LaFarge and Blass among them. The others were obviously men of education also; ruined bankers and financiers, unable to stand the gaff of failure, and slyly engaged in desperate crime.

Agent “X,” the man who had engineered this tremendous victory for the law, the man in down-and-outer’s clothes, stood on the sidelines and watched.

He was at the curb when the members of the devil-dark gang were shoved into Black Marias. Later, in the disguise of A. J. Martin, he went to police headquarters, and was there when the commissioner himself made a statement to the press. The police, the commissioner said, were satisfied. The most fiendishly vicious group of criminals in the city’s history had been rounded up. True, the mechanism by which they created their blinding darkness had been destroyed by fire, its hideous secret kept a mystery, and millions in loot from previous raids were still to be salvaged. But the commissioner was confident that information leading to the recovery of the money could be sweated out of the prisoners. He was confident that not one man of the group had escaped; confident that the menace of the strange darkness would never fall on any city again.

In half-uttered confessions, several of the raiders had indicated that Vivian de Graf had been connected with the band before her death. It was the commissioner’s private belief, he stated, that her murdered husband might have been the originator of the darkness, since it was known that he was a profound worker in science. The commissioner’s smile was complacent as he assured the gentlemen from the press that the whole mystery of how such a group came to organize would be unraveled as soon as his prisoners had confessed.

All this the Secret Agent heard, and a smile twitched at the corners of his lips also; but it was humorless, sardonic. The police commissioner and the whole police department might be satisfied. He was not! And he never would be satisfied, or consider the case closed, until the unknown man behind it all, the mysterious Chairman, who had given the orders at the meeting that others carried out, had been exposed and caught.

Chapter XVIII

MONTHS after the capture and imprisonment of the devil-dark gang, Secret Agent “X” moved through the exhibition rooms of a flower show in a large mid-western city. He was in the disguise of a white-haired, benign looking old man now. There was a silver-headed cane in his hand which seemed a necessary re-enforcement to his faltering steps. Under his left arm was a portfolio containing notes on flowers and copies of horticultural journals.

On both sides of the corridor through which he walked, flowers were banked in a riotous profusion of color. Roses, chrysanthemums, carnations, dahlias, geraniums — all the well-known garden blooms, together with fuchsias, gardenias, and other delicate hothouse blossoms.

The humid air of the big building was heavy with their scent. Flower lovers and horticulturists of all sorts and ages strolled close by. Pretty girls at gaily decorated booths passed out advertising pamphlets, and free sample bouquets. A red-lipped, coquettish miss beckoned to the Agent and laughed up into his face as she drew a red carnation through his buttonhole. He smilingly submitted, then moved on toward the west end of the room where an elaborate arch of blue silk, stretched on a wire framework, had the word “Orchids” emblazoned across it in letters formed of the flowers themselves.

In a moment he was in a chamber filled with thousands of the strangely shaped plants, rarest and most expensive of cultivated blooms. Many looked like bright-colored insects; like butterflies and moths poised for flight. Most of these the Agent, a student of many sciences, knew by name. There were the Habenaria, the Spiranthes and the Oncidium types.

He paused at last before a group of blossoms yellow as saffron and marked with the startling spots of a leopard’s coat or some poisonous reptile’s skin. The flowers were beautiful and exotic; but somehow unwholesome, as though nature had been tortured and tormented for their cultivation. There were no other blooms like them in the whole building.

The eyes of the Secret Agent gleamed as they fastened on these blooms. A faint, humorless smile curved his lips. He seemed a gentle old man bending forward to study the loveliness of rare flowers.

Those who saw him did not guess that the benign and aged face masked the features of the most masterly crime hunter in existence. They did not know that he was on the trail of a criminal at this very moment; that, having sworn never to give up till he had his man, he had waited months to track down and capture one of the most elusive criminals he had ever encountered in his whole career. They did not know that in his pocket at the moment was a telegram in code, written by one of his own trained operatives, which concerned those saffron flowers before him.

Weeks before, the Secret Agent had instructed paid operatives in a score of cities where horticultural exhibitions were scheduled, to get in touch with him if this special variety of saffron orchid appeared. He had equipped these operatives with a detailed colored plate of the flower itself, made from the single blossom he had picked up on the floor of Vivian de Graf’s apartment. For “X” believed that the admirer who sent those orchids to the society beauty was the unknown Chairman of the devil-dark group — the man who had not been caught in the police round-up.

He straightened slowly from before the orchid exhibit, turned his smiling face toward a winsome girl attendant, and beckoned to her.

“These flowers,” he said, “are most beautiful. I would like to learn more about them. Would it be too great an inconvenience to give me their owner’s name and address?”

His voice was smooth, gentle, the soft voice of a polite old man. The girl looked at the number of the exhibit, consulted her register, and wrote a name and address on a slip of paper.

“You’ll find the man who grew them at this address,” she said. “But the flowers are not for sale and neither are the plants. They are here as competitive entries only.”

The Secret Agent thanked her and looked at the paper in his hand. It said: “D. H. Brownell, 36 Rose Hill Road.” Slowly, with the wistful smile still on his face, the Secret Agent moved toward the exhibition’s exit, sniffing from time to time at the spicy fragrance of the carnation in his buttonhole.

He was panting, forty-five minutes later, as he climbed the gentle slope of Rose Hill Road. This was in a wealthy suburban section of the city where the horticultural exhibition had been held. Huge estates with green lawns spreading before them lined the well-kept street. Shade trees arched overhead. The feathery green of spring foliage showed in their interlaced branches. The air here, too, was sweet with the scent of flowers. Crime seemed as remote as some distant star. Yet it was crime’s black trail that had brought Agent “X” away from his usual haunts, brought him on a mission as strange as any he had ever embarked upon.

HIS forward progress was interspersed with frequent halts beside some handy fence to catch his breath and fan himself with the fluttering leaves of a horticultural journal. He was playing the part of an old man well. His silver-headed cane tapping the sidewalk beside his shuffling feet, helped him at last to reach the house marked 36.

Here he rested again, mopping his forehead with a cambric handkerchief. Then he clicked open a gate and moved along a cement walk between rows of ornamental shrubs. The house before him was a large one. It and the grounds showed signs of lavish care and unstinted wealth.

A great dog came bounding toward him, barking furiously. The Agent paused with the timid uncertainty of an aged man and waved his cane at the animal, calling in a cracked voice for some one to check the beast’s rushes.

In a moment a man appeared from the side of the house where he had been supervising the laying out of a new flower bed. That he was not a gardener was evident by his clothes. He was dressed in a stylish, white flannel suit. In contrast to the lightness of the cloth a jet-black beard covered the man’s cheeks and chin and spread magnificently over the whole front of his coat. The rest of his face was ruddy, healthy with the glow of good food and wine and robust living. But there was in the depths of his eyes a certain furtive sharpness, a certain swift calculation, and he glanced suspiciously at his visitor and frowned.

“Here, Daniel!” he cried to the dog. “Stop it! Get back to your kennel!”

The dog flattened its ears, dropped its tail at once, and slunk away, rolling the whites of its eyes at its master, as though grim discipline had taught it to obey. The man turned ungraciously to the white-haired stranger.

“Well — what do you want?” he said.

Secret Agent “X” pushed his handkerchief into his pocket with a deliberately trembling hand. He leaned against his cane, panted for a second or two, then drew an ancient alligator skin wallet from his pocket. He adjusted steel-rimmed glasses on his nose, fumbled in his wallet prodigiously, and finally pulled forth a yellowed card. On this was printed: “Alfred Burpee, Editor Emeritus, Flower Lovers’ Quarterly.” With solemn dignity Secret Agent “X” handed the card to the frowning, bearded man before him.

“Mr. Brownell, I believe,” he said. “It gives me pleasure to introduce myself, and it gives me pleasure also to meet a brother horticulturist of such distinctive taste as yourself.” He waved a hand toward the carefully kept flower beds on all sides. “This is indeed a choice display of garden landscaping you have here. It is what I am in the habit of referring to in my articles as ‘floral chromatization.’ It is, however, what I should expect of a man whose exhibit is the talk of the flower show now being held.”

The bearded man was rolling the stub of a cigar between his moist red lips. His gimlet eyes still bored into the face of the stranger who had introduced himself as Alfred Burpee. There was nothing on that face but guileless admiration and gentle interest. The Agent fumbled in his portfolio and drew out a copy of the Flower Lovers’ Quarterly. He turned the pages eagerly.

“I still do articles for this, Mr. Brownell, though I am a bit too old to stand the exigencies of editorial work. I do articles — and it is my belief that you, if you would be so kind, could give me material for one of the best I have ever done. That you have unusual taste is evident. That you are a man of considerable talent I earnestly believe.”

The bearded man flipped the pages of the magazine “Burpee” had given. The look of suspicion had begun to leave his eyes. His whole manner was growing relaxed. He cleared his throat importantly.

“You saw my orchid exhibit then?”

“I did. And I was so impressed with it that I asked the young lady attendant if I might pay my respects to the owner of such beautiful flowers. She was so kind as to give me your address. And here I am. I hope that you will find it possible to spare a few moments of your time.”

“You want to do an article, eh?”

“Exactly — something with color photos if possible, and—”

A certain grimness came into Brownell’s voice as he interrupted. “I’m sorry — no photos! I don’t like people with cameras walking about — spoiling the flower beds.”

“Then let us say just an article,” the Agent said mildly. “Something that would be helpful to other horticulturists and give them an inkling of how you achieve your success.”

THE bearded Brownell turned and beckoned for Agent “X” to follow. He strode off across the lawn, and “X” admonished him gently.

“Not too fast please — for an old man!”

Brownell showed his visitor many lavish displays of flowers. “X” saw a number of gardeners and their assistants at work. Brownell seemed to have little to do except spend his apparently unlimited resources caring for his estate. Huge greenhouses spread on a spacious lot behind the mansion. Brownell took Agent “X” through these, also. There were many handsome flowers here, many varieties of orchids even; but none of the saffron kind that had been shown at the exhibit. The Agent let wistfulness sound in his voice as he spoke.

“Beautiful! Beautiful!” he said, “but I see you do not keep the precious gold of your special plants in with the more common sorts. Or perhaps the flowers I saw at the show are all you have of that variety. In any case I want to congratulate you on raising some of the handsomest and most unique specimens of the orchid family it has ever been my privilege to behold.”

Pride gleamed in the eyes of Brownell at the Secret Agent’s flattery. He shrugged suddenly. “I did not intend to let any visitors here in on my secret. But after all, there’s no reason why you, Mr. Burpee, shouldn’t know. Come this way, please.”

Agent “X” hid the thrill of excitement he felt. He had played his cards well, played on the vanity of a man to whom no other emotion except fear would appeal. For, that the man before him was vain of his yellow orchids, he had sensed months ago. Otherwise he would not have laid them at the feet of the woman he wished to impress.

Brownell led Agent “X” into the big house itself. It showed signs of recent expensive redecoration. The Agent’s bearded host ushered him down a flight of winding stairs into a cellar room. A door showed at the end of this. Brownell opened it, motioned “X” to enter. He did so, and gasped at what he saw.

For here in this moist chamber, warmed even now by coils of steam pipes; here without any scrap of daylight or vent to the outside air, the prize saffron orchids grew, rearing their spotted yellow heads among jumbled piles of rock, on specially constructed concrete tables. They were everywhere “X” looked, sprouting amid rank green leaves, almost like some startling fungous growth. The plants seemed to be staring at him as though they had life of their own.

He put surprise into his voice, made his eyes widen.

“No sunlight! Good gracious, sir, you mean you raise these lovely flowers in this dark cellar chamber?”

The man who called himself Brownell smiled. “In a cellar chamber — yes. In the dark — no! Look!”

He gestured toward the ceiling where an intricate grillework of glass tubing showed. It seemed somewhat similar to slender Neon lighting tubes, but was arranged differently. No light was visible in them now. The light that revealed the bright flowers came from a big bulb Brownell had switched on when he opened the door.

“There is my sun,” he said. “There is the light the orchids are grown in.”

“Light!” echoed the Agent skeptically, in the tone of a puzzled old man. He adjusted his glasses again, peered up at the gleaming tubing as though to detect some illumination.

AGAIN the man called Brownell laughed in the depths of his wiry black beard. “You can’t see it,” he said. “It is invisible — beyond the range of the spectrum which human eyes can detect. Yet it is there — just as invisible and just as powerful as the ultra-violet rays which can blister the skin. That’s where my orchids get their power to grow, and, because this light is never lacking, I’ve been able to create hybrids never produced before.”

“It is incredible,” said the Agent softly. “You’ve been experimenting with these flowers for years I suppose?”

“Yes, ever since I was a very young man. And it took me a long time to develop this light. I’m proud of it. It’s rather an accomplishment you must admit — and I’m glad I have the leisure to indulge my hobby.”

“An exceedingly constructive hobby,” murmured the Agent. “And a great deal of time and patience must have gone into it.”

“More perhaps than you realize,” said Brownell boastfully. “Very few men would have had the will power to persist. It took me months, even, to gage the right intensity of my ultra-ray light. A trifle too little and the flowers would grow pale and die! A bit too much, and it would literally burn them up. Do you feel anything odd in your head right now?”

The Agent nodded, smiled.

“A slight buzzing it seems. It is most remarkable — and how you can control such a thing is a mystery to me!”

“It would be,” said Brownell superciliously. “But I’ll give you an idea how it’s done.”

He led Agent “X” to the end of the cellar chamber where the saffron orchids grew, opened a door into still another room. No plants showed here. It was filled with complex electrical mechanism. There many small tubes, many elaborate coils of wire, dials and delicate rheostat controls. An electric motor in a dust-proof casing gave out a low, continuous hum.

The tubes in the outer chamber where the plants grew were all connected to one central outlet which went through the wall of this power room. There was a big graduated dial and a leverlike handle near the low-humming motor. It reminded “X” of a control in some great ocean liner.

“There is my light throttle,” said Brownell. “With that I control the invisible candlepower in the next room and in here, too, for the light that those tubes generate can come right through stone walls, right through metal, glass, anything! I have an insulating substance in the outside walls and ceiling, or else, if I turned the lever too far every one in this house might—”

Brownell checked himself suddenly; frowned as though his enthusiasm had made him say a little more than he had meant. He added rather brusquely:

“This branch of my horticultural hobby won’t interest you, Mr. Burpee.”

The Secret Agent was smiling. The wrinkled contours of his disguised face were deceptively gentle. Never had he looked more benign; never more harmless.

“On the contrary, Mr. Brownell,” he said. “I am most interested — fascinated, I might even add! For many months I have wondered how you raised those exquisite orchids.”

“Many months! They have never been on exhibition before!”

“Never on public exhibition — but, you can see how rapt my interest in them has been!”

SLOWLY, while a gradual change came over Brownell’s face, the Secret Agent reached in his pocket. He took out an envelope, took from it a withered flower; one whose yellow spotted petals nevertheless showed. With the flower he displayed a small color plate, made while the bloom was still fresh enough to reveal accurate tints. Brownell’s bearded mouth gaped for a moment.

“Where — where did you get that?” he asked.

“In the apartment of a very lovely lady,” said “X” softly. “In the apartment of Vivian de Graf! It was one of the last of the flowers you sent her — before an assassin’s bullet struck her down. Too bad that your gallant attentions so aroused the jealousy of her devoted husband!”

Brownell made a sound in his throat like a curse. Suddenly, furiously he struck the dried flower and color plate from “X’s” fingers. He stepped back, stood with feet apart, glaring and panting at his white-haired visitor. The change that had come over his face above the beard was startling. It was furious, contorted in its anger, eyes glittering slits, veins standing out on the sweating forehead. It was the face of a hideous, sadistic criminal, the face of a man who, for all his esthetic love of flowers, had the instincts of a ruthless, predatory beast.

“So,” he said. “Alfred Burpee. eh? The editor of a flower journal — interested in orchids — and in the light I raise them by!”

Suddenly Brownell threw back his head, opened a cavern of a mouth in his black beard, and gave vent to hideous laughter. He choked at the end of it, squeezed tears from his eyes. “Light!” he bellowed. “Light, eh!”

With a move so quick that the Agent could barely follow it, he thrust the lever attached to the big dial near the motor all the way to its end stop. The motor’s low hum rose to an ear-splitting whine. Instantly the sensation of buzzing in the Agent’s brain increased. Increased. Instantly the room began to grow dark, and the beaded, distorted features of the man before him began to fade, while Brownell’s wildly evil laughter sounded mockingly. “Light! Light!” he screamed again. “Light — but you can’t see in it!” The bearded criminal had geared up his mechanism, until the blinding darkness, a by-product of his experiments on plants, had descended as it had months ago over the terror-stricken crowds at the points where the raids had taken place.

But Agent “X” was not terror-stricken, not even surprised. As quickly as Brownell had increased the power of the strange mechanism, his own hand darted to his side pocket. He brought out the helmet mask of Emil de Graf, slapped it over his head, and brought the goggles before his eyes.

The invisible rays had not had time to paralyze his optic nerves. The helmet was instantly effective. He could see Brownell adjusting a gleaming helmet on his own head; hear the man bellowing again.

“Light! You’ll get it this time so it will blind you like a mole — blind you so that you’ll never see again as long as you live — if you live. You’ll get so much light it will split your damned head wide open!”

Brownell gave a final tug to the helmet, reached under a shelf in the room, and drew forth one of the wicked, metal-tipped whips that the devil-dark gang had used.

With a thin smile on his lips behind the helmet he wore, Agent “X” gave the knob of his silver-headed cane a twist. The knob came off. He drew from the cane’s hollow interior another long, snakelike whip.

BEFORE Brownell could use his own lash, before he could even turn to see that the man before him was helmeted like himself, Secret Agent “X” struck. His first blow knocked the whip from the other’s hand, brought a screaming curse to Brownell’s amazed lips. His second blow stopped the bearded man’s forward lunge by laying a biting lash across his chest so stingingly that it almost cut the clothing above it.

Brownell instinctively cowered back as the blinded, stricken victims months ago had done. And Agent “X” plied the whip with the memory of those tortured victims’ screams in mind. He plied it ruthlessly, plied it till Brownell had huddled back into the farthest corner of the room, till he was screaming for the Agent to stop, till his coat showed long rents where the metal tips had struck.

Then Agent “X” stepped forward and snatched the helmet from the man’s head. Brownell screamed even more fearfully now.

“The light! The light!” he cried. “It will blind me! Blind me! Turn off the lever for God’s sake!”

Agent “X” stepped forward and put the lever back to the position it had been in when he entered the room. Then he stood over the cowering Brownell with the whip still in his hand. Words, harshly uttered, grated between clenched teeth. The mild old man, “Burpee,” had become a living, human scourge, a champion of justice.

“Your criminal plot was a clever one,” he said. “It seemed foolproof, and it might have been — except for certain things. Your pose as a public defender gave you unusual opportunities to smell out men with criminal instincts and hound them, ruin them, till they were fit material for your plans. And none of them guessed that the man they hated so was actually their leader. None of them knew that the unseen Chairman who directed their activities was actually — Norman Coe!”

The Agent laughed mirthlessly, staring at the bearded, abject man in the corner. “Norman Coe, head of the Citizens Banking Committee, champion of depositors’ rights!”

“X” opened his portfolio, drew out a tablet and a pencil, thrust them into Coe’s hands. The darkness was lifting now. Coe would soon be able to see again even without his mask.

“Write,” said “X” sternly. “Tell exactly how you tricked your own criminal allies as well as the public. Tell how you discovered the blinding ray in your experiments with flowers; how you thought of it as a cover for desperate crime. Tell how you hid the stolen money for a time in one of the closed banks where your Directors’ Room was; and how you retired from your position on the committee after a time, and supposedly left the country for a visit to England.

“Tell how you changed your name to Brownell and planned to spend your stolen millions in luxurious retirement. Tell how your colossal vanity wouldn’t let you resist the temptation to exhibit your prize flowers. Tell everything, Coe, down to the last detail, and sign it! Or, as surely as I stand here, I’ll turn the light lever over again and blind you, and then whip the life out of you as your fiends did the life of Ellen Dowe!”

Under this terrible threat the trembling hand of Norman Coe wrote. Behind his black beard which had seemed an adequate disguise his bloodless face twitched.

When he had finished at last, Agent “X” pocketed the signed confession and suddenly fired his gas gun full in Coe’s face, knocking him unconscious for many minutes to come. He spent a few moments examining the light producing mechanism, then left the underground chamber as he had come. As he passed through the room where the orchids were, he stopped and gasped abruptly. Every poisonous saffron bloom lay wilted and dead, killed by the increased rays that Coe’s frenzy of rage had loosed for a time. The Agent shrugged, moved on out of the cellar chamber and up into the house.

The incurious gardeners at work outside glanced up, and saw only an old, white-haired man shuffling by again. The Agent walked down the hill as he had come. A faint melodious whistle like the strange call of some wild bird floated after him. It was the eerily unique whistle of Secret Agent “X,” and it indicated now that a baffling and unique case was finally finished.

Within twenty minutes after “X” had left the home of “Brownell,” the police head of the city where the yellow orchids had been exhibited, received Coe’s signed confession along with mysterious but precise details concerning the man at 36 Rose Hill Road and the light-producing mechanism in the cellar room. The police head was an intelligent man who kept abreast of the country’s news events. With an inspector and a dozen picked detectives he went at once to round up a criminal whose capture he knew would be a nationwide sensation, a criminal whose extraordinary cunning had taken the skill of a master crime hunter to match.