The Human Edge

I

It was raw, red war for all of them, from the moment the two ships intercepted each other, one degree off the plane of the ecliptic and three diameters out from the second planet of the star that was down on the charts as K94. K94 was a GO type star; and the yelping battle alarm of the trouble horn tumbled sixteen men to their stations. This was at thirteen hours, twenty-one minutes, four seconds of the ship’s day.

Square in the scope of the laser screen, before the Survey Team Leader aboard the Harrier, appeared the gray, light-edged silhouette of a ship unknown to the ship’s library. And the automatic reflexes of the computer aboard, that takes no account of men not yet into their vacuum suits, took over. The Harrier disappeared into no-time.

She came out again at less than a quarter-mile’s distance from the stranger ship and released a five-pound weight at a velocity of five miles a second relative to the velocity of the alien ship. Then she had gone back into no-time again—but not before the alien, with computer-driven reflexes of its own, had rolled like the elongated cylinder it resembled, and laid out a soft green-colored beam of radiation which opened up the Harrier forward like a hot knife through butter left long on the table. Then it too was gone into no-time. The time aboard the Harrier was thirteen hours, twenty-two minutes and eighteen seconds; and on both ships there were dead.

“There are good people in the human race,” Cal Hartlett had written only two months before, to his uncle on Earth, “who feel that it is not right to attack other intelligent beings without warning—to drop five-pound weights at destructive relative velocities on a strange ship simply because you find it at large in space and do not know the race that built it.

“What these gentle souls forget is that when two strangers encounter in space, nothing at all is known—and everything must be. The fates of both races may hinge on which one is first to kill the other and study the unknown carcass. Once contact is made, there is no backing out and no time for consideration. For we are not out here by chance, neither are they, and we do not meet by accident.”

Cal Hartlett was Leader of the Mapping Section aboard the Harrier, and one of those who lived through that first brush with the enemy. He wrote what he wrote as clearly as if he had been Survey Leader and in command of the ship. At any moment up until the final second when it was too late, Joe Aspinall, the Survey Leader, could have taken the Harrier into no-time and saved them. He did not; as no commander of a Survey Ship ever has. In theory, they could have escaped.

In practice, they had no choice.

When the Harrier ducked back into no-time, aboard her they could hear the slamming of emergency bulkheads. The mapping room, the fore weight-discharge room and the sleeping quarters all crashed shut as the atmosphere of the ship whiffed out into space through the wound the enemy’s beam had made. The men beyond the bulkheads and in the damaged sections would have needed to be in their vacuum suits to survive. There had not been time for that, so those men were dead.

The Harrier winked back into normal space.

Her computer had brought her out on the far side of the second planet, which they had not yet surveyed. It was larger than Earth, with somewhat less gravity but a deeper atmospheric envelope. The laser screen picked up the enemy reappearing almost where she had disappeared, near the edge of that atmosphere.

The Harrier winked back all but alongside the other and laid a second five-pound weight through the center of the cylindrical vessel. The other ship staggered, disappeared into no-time and appeared again far below, some five miles above planetary surface in what seemed a desperation attempt to gain breathing time. The Harrier winked after her—and came out within five hundred yards, square in the path of the green beam which it seemed was waiting for her. It opened up the drive and control rooms aft like a red-hot poker lays open a cardboard box.

A few miles below, the surface stretched up the peaks of titanic mountains from horizon to horizon.

“Ram!” yelled the voice of Survey Leader Aspinwall, in warning over the intercom.

The Harrier flung itself at the enemy. It hit like an elevator falling ten stories to a concrete basement. The cylindrical ship broke in half in midair and bodies erupted from it. Then its broken halves and the ruined Harrier were falling separately to the surface below and there was no more time for anyone to look. The clock stood at 13 hrs., 23 minutes and 4 seconds.

The power—except from emergency storage units—was all but gone. As Joe punched for a landing the ship fell angling past the side of a mountain that was a monster among giants, and jarred to a stop. Joe keyed the intercom of the control board before him.

“Report,” he said.

In the Mapping Section Cal Hartlett waited for other voices to speak before him. None came. He thumbed his audio.

“The whole front part of the ship’s dogged shut, Joe,” he said. “No use waiting for anyone up there. So—this is Number Six reporting. I’m all right.”

“Number Seven,” said another voice over the intercom. “Maury. O.K.”

“Number Eight. Sam. O.K.”

“Number Nine. John. O.K….”

Reports went on. Numbers Six through Thirteen reported themselves as not even shaken up. From the rest there was no answer.

In the main Control Section, Joe Aspinwall stared bleakly at his dead control board. Half of his team was dead.

The time was 13 hours, 30 minutes, no seconds.

He shoved that thought from his mind and concentrated on the positive rather than the negative elements of the situation they were in. Cal Hartlett, he thought, was one. Since he could only have eight survivors of his Team, he felt a deep gratitude that Cal should be one of them. He would need Cal in the days to come. And the other survivors of the Team would need him, badly.

Whether they thought so at this moment or not.

“All right,” said Joe, when the voices had ended. “We’ll meet outside the main airlock, outside the ship. There’s no power left to unseal those emergency bulkheads. Cal, Doug, Jeff—you’ll probably have to cut your way out through the ship’s side. Everybody into respirators and warmsuits. According to pre-survey”—he glanced at the instruments before him—“there’s oxygen enough in the local atmosphere for the respirators to extract, so you won’t need emergency bottles. But we’re at twenty-seven thousand three hundred above local sea-level. So it’ll probably be cold—even if the atmosphere’s not as thin here as it would be at this altitude on Earth.” He paused. “Everybody got that? Report!”

They reported. Joe unharnessed himself and got up from his seat. Turning around, he faced Maury Taller.

Maury, rising and turning from his own communications board on the other side of the Section, saw that the Survey Leader’s lean face was set in iron lines of shock and sorrow under his red hair. They were the two oldest members of the Team, whose average age had been in the mid-twenties. They looked at each other without words as they went down the narrow tunnel to the main airlock and, after putting on respirators and warmsuits, out into the alien daylight outside.

The eight of them gathered together outside the arrowhead shape of their Harrier, ripped open fore and aft and as still now as any other murdered thing.

Above them was a high, blue-black sky and the peaks of mountains larger than any Earth had ever known. A wind blew about them as they stood on the side of one of the mountains, on a half-mile wide shelf of tilted rock. It narrowed backward and upward like a dry streambed up the side of the mountain in one direction. In the other it broke off abruptly fifty yards away, in a cliff-edge that hung over eye-shuddering depths of a clefted valley, down in which they could just glimpse a touch of something like jungle greenness.

Beyond that narrow clefted depth lifted the great mountains, like carvings of alien devils too huge to be completely seen from one point alone. Several thousand feet above them on their mountain, the white spill of a glacier flung down a slope that was too steep for ice to have clung to in the heavier gravity of Earth. Above the glacier, which was shaped like a hook, red-gray peaks of the mountain rose like short towers stabbing the blue-dark sky. And from these, even as far down as the men were, they could hear the distant trumpeting and screaming of winds whistling in the peaks.

They took it all in in a glance. And that was all they had time to do. Because in the same moment that their eyes took in their surroundings, something no bigger than a man but tiger-striped and moving with a speed that was more than human, came around the near end of the dead Harrier, and went through the eight men like a predator through a huddle of goats.

Maury Taller and even Cal, who towered half a head over the rest of the men, all were brushed aside like cardboard cutouts of human figures. Sam Cloate, Cal’s assistant in the mapping section, was ripped open by one sweep of a clawed limb as it charged past, and the creature tore out the throat of Mike DeWall with a sideways slash of its jaws. Then it was on Joe Aspinall.

The Survey Team Leader went down under it. Reflex that got metal cuffs on the gloves of his warmsuit up and crossed in front of his throat, his forearms and elbows guarding his belly, before he felt the ferocious weight grinding him into the rock and twisting about on top of him. A snarling, worrying, noise sounded in his ears. He felt teeth shear through the upper part of his thigh and grate on bone.

There was an explosion. He caught just a glimpse of Cal towering oddly above him, a signal pistol fuming in one big hand.

Then the worrying weight pitched itself full upon him and lay still. And unconsciousness claimed him.

II

When Joe came to, his respirator mask was no longer on his face. He was looking out, through the slight waviness of a magnetic bubble field, at ten mounds of small rocks and gravel in a row about twenty feet from the ship. Nine crosses and one six-pointed star. The Star of David would be for Mike DeWall. Joe looked up and saw the unmasked face of Maury Taller looming over him, with the dark outside skin of the ship beyond him.

“How’re you feeling, Joe?” Maury asked.

“All right,” he answered. Suddenly he lifted his head in fright. “My leg—I can’t feel my leg!” Then he saw the silver anesthetic band that was clamped about his right leg, high on the thigh. He sank back with a sigh.

Maury said, “You’ll be all right, Joe.”

The words seemed to trip a trigger in his mind. Suddenly the implications of his damaged leg burst on him. He was the Leader!

“Help me!” he gritted, trying to sit up.

“You ought to lie still.”

“Help me up, I said!” The leg was a dead weight. Maury’s hands took hold and helped raise his body. He got the leg swung off the edge of the surface on which he had been lying, and got into sitting position. He looked around him.

The magnetic bubble had been set up to make a small, air-filled addition of breathable ship’s atmosphere around the airlock entrance of the Harrier. It enclosed about as much space as a good-sized living room. Its floor was the mountain hillside’s rock and gravel. A mattress from one of the ship’s bunks had been set up on equipment boxes to make him a bed. At the other end of the bubble-enclosed space something as big as a man was lying zippered up in a gray cargo freeze-sack.

“What’s that?” Joe demanded. “Where’s everybody?”

“They’re checking equipment in the damaged sections,” answered Maury. “We shot you full of medical juices. You’ve been out about twenty hours. That’s about three-quarters of a local day-and-night cycle locally, here.” He grabbed the wounded man’s shoulders suddenly with both hands. “Hold it! What’re you trying to do?”

“Have a look in that freeze-sack there,” grunted the Team Leader between his teeth. “Let go of me, Maury. I’m still in charge here!”

“Sit still,” said Maury. “I’ll bring it to you.”

He went over to the bag, taking hold of one of the carrying handles he dragged it back. It came easily in the lesser gravity, only a little more than eight-tenths of Earth’s. He hauled the thing to the bed and unzipped it.

Joe stared. What was inside was not what he had been expecting.

“Cute, isn’t it?” said Maury.

They looked down at the hard-frozen gray body of a biped, with the back of its skull shattered and burnt by the flare of a signal pistol. It lay on its back. The legs were somewhat short for the body and thick, as the arms were thick. But elbow and knee joints were where they should be, and the hands had four stubby gray fingers, each with an opposed thumb. Like the limbs, the body was thick—almost waistless. There were deep creases, as if tucks had been taken in the skin, around the body under the armpits, around the waist and around the legs and arms.

The head, though, was the startling feature. It was heavy and round as a ball, sunk into thick folds of neck and all but featureless. Two long slits ran down each side into the neck and shoulder area. The slits were tight closed. Like the rest of the body, the head had no hair. The eyes were little pock-marks, like raisins sunk into a doughball, and there were no visible brow ridges. The nose was a snout-end set almost flush with the facial surface. The mouth was lipless, a line of skin folded together, through which now glinted barely a glimpse of close-set, large, tridentated teeth.

“What’s this?” said Joe. “Where’s the thing that attacked us?”

“This is it,” said Maury. “One of the aliens from the other ship.”

Joe stared at him. In the brighter, harsher light from the star K94 overhead, he noticed for the first time a sprinkling of gray hairs in the black shock above Maury’s spade-shaped face. Maury was no older than Joe himself.

“What’re you talking about?” said Joe. “I saw that thing that attacked me. And this isn’t it!”

“Look,” said Maury and turned to the foot of the bed. From one of the equipment boxes he brought up eight by ten inch density photographs. “Here,” he said, handing them to the Survey Team Leader. “The first one is set for bone density.”

Joe took them. It showed the skeleton of the being at his feet… and it bore only a relative kinship to the shape of the being itself.

Under the flesh and skin that seemed so abnormally thick, the skull was high-forebrained and well developed. Heavy brown ridges showed over deep wells for the eyes. The jaw and teeth were the prognathous equipment of a carnivorous animal.

But that was only the beginning of the oddities. Bony ridges of gill structures were buried under a long fold on either side of the head, neck and shoulders. The rib cage was enormous and the pelvis tiny, buried under eight or nine inches of the gray flesh. The limbs were literally double-jointed. There was a fantastic double structure of ball and socket that seemed wholly unnecessary. Maury saw the Survey Leader staring at one hip joint and leaned over to tap it with the blunt nail of his forefinger.

“Swivel and lock,” said Maury. “If the joint’s pulled out, it can turn in any direction. Then, if the muscles surrounding it contract, the two ball joints interlace those bony spurs there and lock together so that they operate as a single joint in the direction chosen. That hip joint can act like the hip joint on the hind leg of a quadruped, or the leg of a biped. It can even adapt for jumping and running with maximum efficiency.—Look at the toes and the fingers.”

Joe looked. Hidden under flesh, the bones of feet and hands were not stubby and short, but long and powerful. And at the end of finger and toe bones were the curved, conical claws they had seen rip open Sam Cloate with one passing blow.

“Look at these other pictures now,” said Maury, taking the first one off the stack Joe held. “These have been set for densities of muscle—that’s this one here—and fat. Here. And this one is set for soft internal organs—here.” He was down to the last. “And this one was set for the density of the skin. Look at that. See how thick it is, and how great folds of it are literally tucked away underneath in those creases.

“Now,” said Maury, “look at this closeup of a muscle. See how it resembles an interlocking arrangement of innumerable tiny muscles? Those small muscles can literally shift to adapt to different skeletal positions. They can take away beef from one area and add it to an adjoining area. Each little muscle actually holds on to its neighbors, and they have little sphincter-sealed tube-systems to hook on to whatever blood-conduit is close. By increased hookup they can increase the blood supply to any particular muscle that’s being overworked. There’s parallel nerve connections.”

Maury stopped and looked at the other man.

“You see?” said Maury. “This alien can literally be four or five different kinds of animal. Even a fish! And no telling how many varieties of each kind. We wondered a little at first why he wasn’t wearing any kind of clothing, but we didn’t wonder after we got these pictures. Why would he need clothing when he can adapt to any situation—Joe!” said Maury. “You see it, don’t you? You see the natural advantage these things have over us all?”

Joe shook his head.

“There’s no body hair,” he said. “The creature that jumped me was striped like a tiger.”

“Pigmentation. In response to emotion, maybe,” said Maury. “For camouflage—or for terrifying the victims.”

Joe sat staring at the pictures in his hand.

“All right,” he said after a bit. “Then tell me how he happened to get here three or four minutes after we fell down here ourselves? And where did he come from? We rammed that other ship a good five miles up.”

“There’s only one way, the rest of us figured it out,” said Maury. “He was one of the ones who were spilled out when we hit them. He must have grabbed our hull and ridden us down.”

“That’s impossible!”

“Not if he could flatten himself out and develop suckers like a starfish,” said Maury. “The skin picture shows he could.”

“All right,” said Joe. “Then why did he try a suicidal trick like that attack—him alone against the eight of us?”

“Maybe it wasn’t so suicidal,” said Maury. “Maybe he didn’t see Cal’s pistol and thought he could take the unarmed eight of us.” Maury hesitated. “Maybe he could, too. Or maybe he was just doing his duty—to do as much damage to us as he could before we got him. There’s no cover around here that’d have given him a chance to escape from us. He knew that we’d see him the first time he moved.”

Joe nodded, looking down at the form in the freeze-sack. For the aliens of the other ship there would be one similarity with the humans—a duty either to get home themselves with the news of contact, at all costs; or failing that, to see their enemy did not get home.

For a moment he found himself thinking of the frozen body before him almost as if it had been human. From what strange home world might this individual now be missed forever? And what thoughts had taken place in that round, gray-skinned skull as it had fallen surfaceward clinging to the ship of its enemies, seeing the certainty of its own death approaching as surely as the rocky mountainside?

“Do we have record films of the battle?” Joe asked.

“I’ll get them.” Maury went off.

He brought the films. Joe, feeling the weakness of his condition stealing up on him, pushed it aside and set to examining the pictorial record of the battle. Seen in the film viewer, the battle had a remote quality. The alien ship was smaller than Joe had thought, half the size of the Harrier. The two dropped weights had made large holes in its midships. It was not surprising that it had broken apart when rammed.

One of the halves of the broken ship had gone up and melted in a sudden flare of green light like their weapons beam, as if some internal explosion had taken place. The other half had fallen parallel to the Harrier and almost as slowly—as if the fragment, like the dying Harrier, had had yet some powers of flight—and had been lost to sight at last on the opposite side of this mountain, still falling.

Four gray bodies had spilled from the alien ship as it broke apart. Three, at least, had fallen some five miles to their deaths. The record camera had followed their dwindling bodies. And Maury was right; these had been changing even as they fell, flattening and spreading out as if in an instinctive effort to slow their fall. But, slowed or not, a five-mile fall even in this lesser-than-Earth gravity was death.

Joe put the films aside and began to ask Maury questions.

The Harrier, Maury told him, would never lift again. Half her drive section was melted down to magnesium alloy slag. She lay here with food supplies adequate for the men who were left for four months. Water was no problem as long as everyone existed still within the ship’s recycling system. Oxygen was available in the local atmosphere and respirators would extract it. Storage units gave them housekeeping power for ten years. There was no shortage of medical supplies, the tool shop could fashion ordinary implements, and there was a good stock of usual equipment.

But there was no way of getting off this mountain.

III

The others had come into the bubble while Maury had been speaking. They stood now around the bed. With the single exception of Cal, who showed nothing, they all had a new, taut, skinned-down look about their faces, like men who have been recently exhausted or driven beyond their abilities.

“Look around you,” said Jeff Ramsey, taking over from Maury when Maury spoke of the mountain. “Without help we can’t leave here.”

“Tell him,” said Doug Kellas. Like young Jeff, Doug had not shaved recently. But where Jeff’s stubble of beard was blond, Doug’s was brown-dark and now marked out the hollows under his youthful cheekbones. The two had been the youngest of the Team.

“Well, this is a hanging valley,” said Jeff. Jeff was the surface man geologist and meteorologist of the Team. “At one time a glacier used to come down this valley we’re lying in, and over that edge there. Then the valley subsided, or the mountain rose or the climate changed. All the slopes below that cliff edge—any way down from here—brings you finally to a sheer cliff.”

“How could the land raise that much?” murmured Maury, looking out and down at the green too far below to tell what it represented. Jeff shrugged.

“This is a bigger world than Earth—even if it’s lighter,” he said. “Possibly more liable to crustal distortion.” He nodded at the peaks above them. “These are young mountains. Their height alone reflects the lesser gravity. That glacier up there couldn’t have formed on that steep a slope on Earth.”

“There’s the Messenger,” said Cal.

His deeper-toned voice brought them all around. He had been standing behind the rest, looking over their heads. He smiled a little dryly and sadly at the faint unanimous look of hostility on the faces of all but the Survey Leader’s. He was unusual in the respect that he was so built as not to need their friendship. But he was a member of the Team as they were and he would have liked to have had that friendship—if it could have been had at any price short of changing his own naturally individualistic character.

“There’s no hope of that,” said Doug Kellas. “The Messenger was designed for launching from the ship in space. Even in spite of the lower gravity here, it’d never break loose of the planet.”

The Messenger was an emergency device every ship carried. It was essentially a miniature ship in itself, with drive unit and controls for one shift through no-time and an attached propulsive unit to kick it well clear of any gravitic field that might inhibit the shift into no-time. It could be set with the location of a ship wishing to send a message back to Earth, and with the location of Earth at the moment of arrival—both figured in terms of angle and distance from the theoretical centerpoint of the galaxy, as determined by ship’s observations. It would set off, translate itself through no-time in one jump back to a reception area just outside Earth’s critical gravitic field, and there be picked up with the message it contained.

For the Harrier team, this message could tell of the aliens and call for rescue. All that was needed was the precise information concerning the Harrier’s location in relation to Galactic Centerpoint and Earth’s location.

In the present instance, this was no problem. The ship’s computer log developed the known position and movement of Earth with regard to Centerpoint, with every shift and movement of the ship. And the position of the second planet of star K94 was known to the chartmakers of Earth recorded by last observation aboard the Harrier.

Travel in no-time made no difficulty of distance. In no-time all points coincided, and the ship was theoretically touching them all. Distance was not important, but location was. And a precise location was impossible—the very time taken to calculate it would be enough to render it impossibly inaccurate. What ships travelling by no-time operated on were calculations approximately as correct as possible—and leave a safety factor, read the rulebook.

Calculate not to the destination, but to a point safely short enough of it, so that the predictable error will not bring the ship out in the center of some solid body. Calculate safely short of the distance remaining… and so on by smaller and smaller jumps to a safe conclusion.

But that was with men aboard. With a mechanical unit like the Messenger, a one-jump risk could be taken.

The Harrier had the figures to risk it—but a no-time drive could not operate within the critical area of a gravitic field like this planet’s. And, as Jeff had said, the propulsive unit of the Messenger was not powerful enough to take off from this mountainside and fight its way to escape from the planet

“That was one of the first things I figured,” said Jeff, now. “We’re more than four miles above this world’s sea-level, but it isn’t enough. There’s too much atmosphere still above us.”

“The Messenger’s only two and a half feet long put together,” said Maury. “It only weighs fifteen pounds earthside. Can’t we send it up on a balloon or something? Did you think of that?”

“Yes,” said Jeff. “We can’t calculate exactly the time it would take for a balloon to drift to a firing altitude, and we have to know the time to set the destination controls. We can’t improvise any sort of a booster propulsion unit for fear of jarring or affecting the destination controls. The Messenger is meant to be handled carefully and used in just the way it’s designed to be used, and that’s all.” He looked around at them. “Remember, the first rule of a Survey Ship is that it never lands anywhere but Earth.”

“Still,” said Cal, who had been calmly waiting while they talked this out, “we can make the Messenger work.”

“How?” challenged Doug, turning on him. “Just how?”

Cal turned and pointed to the wind-piping battlemented peaks of the mountain looming far above.

“I did some calculating myself,” he said. “If we climb up there and send the Messenger off from the top, it’ll break free and go.”

None of the rest of them said anything for a moment. They had all turned and were looking up the steep slope of the mountain, at the cliffs, the glacier where no glacier should be able to hang, and the peaks.

“Any of you had any mountain-climbing experience?” asked Joe.

“There was a rock-climbing club at the University I went to,” said Cal. “They used to practice on the rock walls of the bluffs on the St. Croix River—that’s about sixty miles west of Minneapolis and St. Paul. I went out with them a few times.”

No one else said anything. Now they were looking at Cal.

“And,” said Joe, “as our nearest thing to an expert, you think that”—he nodded to the mountain—“can be climbed carrying the Messenger along?”

Cal nodded.

“Yes,” he said slowly. “I think it can. I’ll carry the Messenger myself. We’ll have to make ourselves some equipment in the tool shop, here at the ship. And I’ll need help going up the mountain.”

“How many?” said Joe.

“Three.” Cal looked around at them as he called their names. “Maury, Jeff and Doug. All the able-bodied we’ve got.”

Joe was growing paler with the effort of the conversation.

“What about John?” he asked looking past Doug at John Martin, Number Nine of the Survey Team. John was a short, rugged man with wiry hair—but right now his face was almost as pale as Joe’s, and his warmsuit bulged over the chest.

“John got slashed up when he tried to pull the alien off you,” said Cal calmly. “Just before I shot. He got it clear across the pectoral muscles at the top of his chest. He’s no use to me.”

“I’m all right,” whispered John. It hurt him even to breathe and he winced in spite of himself at the effort of talking.

“Not all right to climb a mountain,” said Cal. “I’ll take Maury, Jeff and Doug.”

“All right. Get at it then.” Joe made a little, awkward gesture with his hand, and Maury stooped to help pull the pillows from behind him and help him lie down. “All of you—get on with it.”

“Come with me,” said Cal. “I’ll show you what we’re going to have to build ourselves in the tool shop.”

“I’ll be right with you,” said Maury. The others went off. Maury stood looking down at Joe. They had been friends and teammates for some years.

“Shoot,” whispered Joe weakly, staring up at him. “Get it off your chest, whatever it is, Maury.” The effort of the last few minutes was beginning to tell on Joe. It seemed to him the bed rocked with a seasick motion beneath him, and he longed for sleep.

“You want Cal to be in charge?” said Maury, staring down at him.

Joe lifted his head from the pillow. He blinked and made an effort and the bed stopped moving for a moment under him.

“You don’t think Cal should be?” he said.

Maury simply looked down at him without words. When men work and sometimes die together as happens with tight units like a Survey Team, there is generally a closeness amongst them. This closeness, or the lack of it, is something that is not easily talked about by the men concerned.

“All right,” Joe said. “Here’s my reasons for putting him in charge of this. In the first place he’s the only one who’s done any climbing. Secondly, I think the job is one he deserves.” Joe looked squarely back up at the man who was his best friend on the Team. “Maury, you and the rest don’t understand Cal. I do. I know that country he was brought up in and I’ve had access to his personal record. You all blame him for something he can’t help.”

“He’s never made any attempt to fit in with the Team—”

“He’s not built to fit himself into things. Maury—” Joe struggled up on one elbow. “He’s built to make things fit him. Listen, Maury—he’s bright enough, isn’t he?”

“I’ll give him that,” said Maury, grudgingly.

“All right,” said Joe. “Now listen. I’m going to violate Department rules and tell you a little bit about what made him what he is. Did you know Cal never saw the inside of a formal school until he was sixteen—and then the school was a university? The uncle and aunt who brought him up in the old voyageur’s-trail area of the Minnesota-Canadian border were just brilliant enough and nutty enough to get Cal certified for home education. The result was Cal grew up in the open woods, in a tight little community that was the whole world, as far as he was concerned. And that world was completely indestructible, reasonable and handleable by young Cal Hartlett.”

“But—”

“Let me talk, Maury. I’m going to this much trouble,” said Joe, with effort, “to convince you of something important. Add that background to Cal’s natural intellect and you get a very unusual man. Do you happen to be able to guess what Cal’s individual sense of security rates out at on the psych profile?”

“I suppose it’s high,” said Maury.

“It isn’t simply high—it just isn’t,” Joe said. “He’s off the scale. When he showed up at the University of Minnesota at sixteen and whizzed his way through a special ordering of entrance exams, the psychology department there wanted to put him in a cage with the rest of the experimental animals. He couldn’t see it. He refused politely, took his bachelor’s degree and went into Survey Studies. And here he is.” Joe paused. “That’s why he’s going to be in charge. These aliens we’ve bumped into could be the one thing the human race can’t match. We’ve got to get word home. And to get word home, we’ve got to get someone with the Messenger to the top of that mountain.”

He stopped talking. Maury stood there.

“You understand me, Maury?” said Joe. “I’m Survey Leader. It’s my responsibility. And in my opinion if there’s one man who can get the Messenger to the top of the mountain, it’s Cal.”

The bed seemed to make a slow half-swing under him suddenly. He lost his balance. He toppled back off the support of his elbow, and the sky overhead beyond the bubble began to rotate slowly around him and things blurred.

Desperately he fought to hold on to consciousness. He had to convince Maury, he thought. If he could convince Maury, the others would fall in line. He knew what was wrong with them in their feelings toward Cal as a leader. It was the fact that the mountain was unclimbable. Anyone could see it was unclimbable. But Cal was going to climb it anyway, they all knew that, and in climbing it he would probably require the lives of the men who went with him.

They would not have minded that if he had been one of them. But he had always stood apart, and it was a cold way to give your life—for a man whom you had never understood, or been able to get close to.

“Maury,” he choked. “Try to see it from Cal’s—try to see it from his—”

The sky spun into a blur. The world blurred and tilted.

“Orders,” Joe croaked at Maury. “Cal—command—”

“Yes,” said Maury, pressing him back down on the bed as he tried blindly to sit up again. “All right. All right, Joe. Lie still. He’ll have the command. He’ll be in charge and we’ll all follow him. I promise…”

IV

During the next two days, the Survey Leader was only intermittently conscious. His fever ran to dangerous levels, and several times he trembled and jerked as if on the verge of going into convulsions. John Martin also, although he was conscious and able to move around and even do simple tasks, was pale, high-fevered and occasionally thick-tongued for no apparent reason. It seemed possible there was an infective agent in the claw and teeth wounds made by the alien, with which the ship’s medicines were having trouble coping.

With the morning of the third day when the climbers were about to set out both men showed improvement.

The Survey Leader came suddenly back to clearheadedness as Cal and the three others were standing, all equipped in the bubble, ready to leave. They had been discussing last-minute warnings and advices with a pale but alert John Martin when Joe’s voice entered the conversation.

“What?” it said. “Who’s alive? What was that?”

They turned and saw him propped up on one elbow on his makeshift bed. They had left him on it since the sleeping quarters section of the ship had been completely destroyed, and the sections left unharmed were too full of equipment to make practical places for the care of a wounded man. Now they saw his eyes taking in their respirator masks, packs, hammers, the homemade pitons and hammers, and other equipment including rope, slung about them.

“What did one of you say?” Joe demanded again. “What was it?”

“Nothing, Joe,” said John Martin, coming toward him. “Lie down.”

Joe waved him away, frowning. “Something about one being still alive. One what?”

Cal looked down at him. Joe’s face had grown lean and fallen in even in these few days but the eyes in the face were sensible.

“He should know,” Cal said. His calm, hard, oddly carrying baritone quieted them all. “He’s still Survey Leader.” He looked around at the rest but no one challenged his decision. He turned and went into the corridor of the ship, down to the main control room, took several photo prints from a drawer and brought them back. When he got back out, he found Joe now propped up on pillows but waiting.

“Here,” said Cal, handing Joe the photos. “We sent survey rockets with cameras over the ridge up there for a look at the other side of the mountain. That top picture shows you what they saw.”

Joe looked down at the top picture that showed a stony mountainside steeper than the one the Harrier lay on. On this rocky slope was what looked like the jagged, broken-off end of a blackened oil drum—with something white spilled out on the rock by the open end of the drum.

“That’s what’s left of the alien ship,” said Cal. “Look at the closeup on the next picture.”

Joe discarded the top photo and looked at the one beneath. Enlarged in the second picture he saw that the white something was the body of an alien, lying sprawled out and stiff.

“He’s dead, all right,” said Cal. “He’s been dead a day or two anyway. But take a good look at the whole scene and tell me how it strikes you.”

Joe stared at the photo with concentration. For a long moment he said nothing. Then he shook his head, slowly.

“Something’s phony,” he said at last, huskily.

“I think so too,” said Cal. He sat down on the makeshift bed beside Joe and his weight tilted the wounded man a little toward him. He pointed to the dead alien. “Look at him. He’s got nothing in the way of a piece of equipment he was trying to put outside the ship before he died. And that mountainside’s as bare as ours. There was no place for him to go outside the ship that made any sense as a destination if he was that close to dying. And if you’re dying on a strange world, do you crawl out of the one familiar place that’s there with you?”

“Not if you’re human,” said Doug Kellas behind Cal’s shoulder. There was the faintly hostile note in Doug’s voice still. “There could be a dozen different reasons we don’t know anything about. Maybe it’s taboo with them to die inside a spaceship. Maybe he was having hallucinations at the end, that home was just beyond the open end of the ship. Anything.”

Cal did not bother to turn around.

“It’s possible you’re right, Doug,” he said. “They’re about our size physically and their ship was less than half the size of the Harrier. Counting this one in the picture and the three that fell with the one that we killed here, accounts for five of them. But just suppose there were six. And the sixth one hauled the body of this one outside in case we came around for a look—just to give us a false sense of security thinking they were all gone.”

Joe nodded slowly. He put the photos down on the bed and looked at Cal who stood up.

“You’re carrying guns?” said Joe. “You’re all armed in case?”

“We’re starting out with sidearms,” said Cal. “Down here the weight of them doesn’t mean much. But up there…” He nodded to the top reaches of the mountain and did not finish. “But you and John better move inside the ship nights and keep your eyes open in the day.”

“We will.” Joe reached up a hand and Cal shook it. Joe shook hands with the other three who were going. They put their masks on.

“The rest of you ready?” asked Cal, who by this time was already across the bubble enclosure, ready to step out. His voice came hollowly through his mask. The others broke away from Joe and went toward Cal, who stepped through the bubble.

“Wait!” said Joe suddenly from the bed. They turned to him. He lay propped up, and his lips moved for a second as if he was hunting for words. “—Good luck!” he said at last.

“Thanks,” said Cal for all of them. “To you and John, too. We’ll all need it.”

He raised a hand in farewell. They turned and went.

They went away from the ship, up the steep slope of the old glacier stream bed that became more steep as they climbed. Cal was in the lead with Maury, then Jeff, then Doug bringing up the rear. The yellow bright rays of K94 struck back at them from the ice-scoured granite surface of the slope, gray with white veinings of quartz. The warmsuits were designed to cool as well as heat their wearers, but they had been designed for observer-wearers, not working wearers. At the bend-spots of arm and leg joints, the soft interior cloth of the warmsuits soon became damp with sweat as the four men toiled upward. And the cooling cycle inside the suits made these damp spots clammy-feeling when they touched the wearer. The respirator masks also became slippery with perspiration where the soft, elastic rims of their transparent faceplates pressed against brow and cheek and chin. And to the equipment-heavy men the feel of the angle of the steep rock slope seemed treacherously less than eyes trained to Earth gravity reported it. Like a subtly tilted floor in a fun house at an amusement park.

They climbed upward in silence as the star that was larger than the sun of Earth climbed in the sky at their backs. They moved almost mechanically, wrapped in their own thoughts. What the other three thought were personal, private thoughts having no bearing on the moment. But Cal in the lead, his strong-boned, rectangular face expressionless, was wrapped up in two calculations. Neither of these had anything to do with the angle of the slope or the distance to the top of the mountain.

He was calculating what strains the human material walking behind him would be able to take. He would need more than their-grudging cooperation. And there was something else.

He was thinking about water.

Most of the load carried by each man was taken up with items constructed to be almost miraculously light and compact for the job they would do. One exception was the fifteen Earth pounds of components of the Messenger, which Cal himself carried in addition to his mountain-climbing equipment—the homemade crampons, pitons and ice axe-piton hammer—and his food and the sonic pistol at his belt. Three others were the two-gallon containers of water carried by each of the other three men. Compact rations of solid food they all carried, and in a pinch they could go hungry. But to get to the top of the mountain they would need water.

Above them were ice slopes, and the hook-shaped glacier that they had been able to see from the ship below.

That the ice could be melted to make drinking water was beyond question. Whether that water would be safe to drink was something else. There had been the case of another Survey ship on another world whose melted local ice water had turned out to contain as a deposited impurity a small wind-born organism that came to life in the inner warmth of men’s bodies and attacked the walls of their digestive tracts. To play safe here, the glacier ice would have to be distilled.

Again, one of the pieces of compact equipment Cal himself carried was a miniature still. But would he still have it by the time they reached the glacier? They were all ridiculously overloaded now.

Of that overload, only the Messenger itself and the climbing equipment, mask and warmsuit had to be held on to at all costs. The rest could and probably would go. They would probably have to take a chance on the melted glacier ice. If the chance went against them—how much water would be needed to go the rest of the way?

Two men at least would have to be supplied. Only two men helping each other could make it all the way to the top. A single climber would have no chance.

Cal calculated in his head and climbed. They all climbed.

From below, the descending valley stream bed of the former glacier had looked like not too much of a climb. Now that they were on it, they were beginning to appreciate the tricks the eye could have played upon it by sloping distances in a lesser gravity, where everything was constructed to a titanic scale. They were like ants inching up the final stories of the Empire State Building.

Every hour they stopped and rested for ten minutes. And it was nearly seven hours later, with K94 just approaching its noon above them, that they came at last to the narrowed end of the ice-smoothed rock, and saw, only a few hundred yards ahead, the splintered and niched vertical rock wall they would have to climb to the foot of the hook-shaped glacier.

V

They stopped to rest before tackling the distance between them and the foot of the rock wall. They sat in a line on the bare rock, facing downslope, their packloads leaned back against the higher rock. Cal heard the sound of the others breathing heavily in their masks, and the voice of Maury came somewhat hollowly through the diaphragm of his mask.

“Lots of loose rock between us and that cliff,” said the older man. “What do you suppose put it there?”

“It’s talus,” answered Jeff Ramsey’s mask-hollowed voice from the far end of the line. “Weathering—heat differences, or maybe even ice from snowstorms during the winter season getting in cracks of that rock face, expanding, and cracking off the sedimentary rock it’s constructed of. All that weathering’s made the wall full of wide cracks and pockmarks, see?”

Cal glanced over his shoulder.

“Make it easy to climb,” he said. And heard the flat sound of his voice thrown back at him inside his mask. “Let’s get going. Everybody up!”

They got creakily and protestingly to their feet. Turning, they fell into line and began to follow Cal into the rock debris, which thickened quickly until almost immediately they were walking upon loose rock flakes any size up to that of a garage door, that slipped or slid unexpectedly under their weight and the angle of this slope that would not have permitted such an accumulation under Earth’s greater gravity.

“Watch it!” Cal threw back over his shoulder at the others. He had nearly gone down twice when loose rock under his weight threatened to start a miniature avalanche among the surrounding rock. He labored on up the talus slope, hearing the men behind swearing and sliding as they followed.

“Spread out!” he called back. “So you aren’t one behind the other—and stay away from the bigger rocks.”

These last were a temptation. Often as big as a small platform, they looked like rafts floating on top of the smaller shards of rock, the similarity heightened by the fact that the rock of the cliff-face was evidently planar in structure. Nearly all the rock fragments split off had flat faces. The larger rocks seemed to offer a temptingly clear surface on which to get away from the sliding depth of smaller pieces in which the boots of the men’s warmsuits went mid-leg deep with each sliding step. But the big fragments, Cal had already discovered, were generally in precarious balance on the loose rock below them and the angled slope. The lightest step upon them was often enough to make them turn and slide.

He had hardly called the warning before there was a choked-off yell from behind him and the sound of more-than-ordinary roaring and sliding of rock.

He spun around. With the masked figures of Maury on his left and Doug on his right he went scrambling back toward Jeff Ramsey, who was lying on his back, half-buried in rock fragments and all but underneath a ten by six foot slab of rock that now projected reeflike from the smaller rock pieces around it

Jeff did not stir as they came up to him, though he seemed conscious. Cal was first to reach him. He bent over the blond-topped young man and saw through the faceplate of the respirator mask how Jeff’s lips were sucked in at the corners and the skin showed white in a circle around his tight mouth.

“My leg’s caught.” The words came tightly and hollowly through the diaphragm of Jeff’s mask. “I think something’s wrong with it.”

Carefully, Cal and the others dug the smaller rock away. Jeff’s right leg was pinned down under an edge of the big rock slab. By extracting the rock underneath it piece by piece, they got the leg loose. But it was bent in a way it should not have been.

“Can you move it?”

Jeff’s face stiffened and beaded with sweat behind the mask faceplate.

“No.”

“It’s broken, all right,” said Maury. “One down already,” he added bitterly. He had already gone to work, making a splint from two tent poles out of Jeff’s pack. He looked up at Cal as he worked, squatting beside Jeff. “What do we do now, Cal? We’ll have to carry him back down?”

“No,” said Cal. He rose to his feet. Shading his eyes against the sun overhead he looked down the hanging valley to the Harrier, tiny below them.

They had already used up nearly an hour floundering over the loose rock, where one step forward often literally had meant two steps sliding backward. His timetable, based on his water supplies, called for them to be at the foot of the ice slope leading to the hook glacier before camping for the night—and it was already noon of the long local day.

“Jeff,” he said. “You’re going to have to get back down to the Harrier by yourself.” Maury started to protest, then shut up. Cal could see the other men looking at him.

Jeff nodded. “All right,” he said. “I can make it. I can roll most of the way.” He managed a grin.

“How’s the leg feel?”

“Not bad, Cal.” Jeff reached out a warmsuited hand and felt the leg gingerly. “More numb than anything right now.”

“Take his load off,” said Cal to Doug. “And give him your morphine pack as well as his own. We’ll pad that leg and wrap it the best we can, Jeff, but it’s going to be giving you a rough time before you get it back to the ship.”

“I could go with him to the edge of the loose rock—” began Doug, harshly.

“No. I don’t need you. Downhill’s going to be easy,” said Jeff.

“That’s right,” said Cal. “But even if he did need you, you couldn’t go, Doug. I need you to get to the top of that mountain.”

They finished wrapping and padding the broken leg with one of the pup tents and Jeff started off, half-sliding, half dragging himself downslope through the loose rock fragments.

They watched him for a second. Then, at Cal’s order, they turned heavily back to covering the weary, strugglesome distance that still separated them from the foot of the rock face.

They reached it at last and passed into the shadow at its base. In the sunlight of the open slope the warmsuits had struggled to cool them. In the shadow, abruptly, the process went the other way. The cliff of the rock face was about two hundred feet in height, leading up to that same ridge over which the weather balloon had been sent to take pictures of the fragment of alien ship on the other side of the mountain. Between the steep rock walls at the end of the glacial valley, the rock face was perhaps fifty yards wide. It was torn and pocked and furrowed vertically by the splitting off of rock from it. It looked like a great chunk of plank standing on end, weathered along the lines of its vertical grain into a decayed roughness of surface.

The rock face actually leaned back a little from the vertical, but, looking up at it from its foot, it seemed not only to go straight up, but—if you looked long enough—to overhang, as if it might come down on the heads of the three men. In the shadowed depths of vertical cracks and holes, dark ice clung.

Cal turned to look back the way they had come. Angling down away behind them, the hanging valley looked like a giant’s ski-jump. A small, wounded creature that was the shape of Jeff was dragging itself down the slope, and a child’s toy, the shape of the Harrier, lay forgotten at the jump’s foot.

Cal turned back to the cliff and said to the others, “Rope up.”

He had already shown them how this was to be done, and they had practiced it back at the Harrier. They tied themselves together with the length of sounding line, the thinness of which Cal had previously padded and thickened so that a man could wrap it around himself to belay another climber without being cut in half. There was no worry about the strength of the sounding line.

“All right,” said Cal, when they were tied together—himself in the lead, Maury next, Doug at the end. “Watch where I put my hands and feet as I climb. Put yours in exactly the same places.”

“How’ll I know when to move?” Doug asked hollowly through his mask.

“Maury’ll wave you on, as I’ll wave him on,” said Cal. Already they were high enough up for the whistling winds up on the mountain peak to interfere with mask-impeded conversations conducted at a distance. “You’ll find this cliff is easier than it looks. Remember what I told you about handling the rope. And don’t look down.”

“All right.”

Cal had picked out a wide rock chimney rising twenty feet to a little ledge of rock. The inner wall of the chimney was studded with projections on which his hands and feet could find purchase. He began to climb.

When he reached the ledge he was pleasantly surprised to find that, in spite of his packload, the lesser gravity had allowed him to make the climb without becoming winded. Maury, he knew, would not be so fortunate. Doug, being the younger man and in better condition, should have less trouble, which was why he had put Doug at the end, so that they would have the weak man between them.

Now Cal stood up on the ledge, braced himself against the rock wall at his back and belayed the rope by passing it over his left shoulder, around his body and under his right arm.

He waved Maury to start climbing. The older man moved to the wall and began to pull himself up as Cal took in the slack of the rope between them.

Maury climbed slowly but well, testing each hand and foothold before he trusted his weight to it. In a little while he was beside Cal on the ledge, and the ascent of Doug began. Doug climbed more swiftly, also without incident. Shortly they were all on the ledge.

Cal had mapped out his climb on this rock face before they had left, studying the cliff with powerful glasses from the Harrier below. Accordingly, he now made a traverse, moving horizontally across the rock face to another of the deep, vertical clefts in the rock known as chimneys to climbers. Here he belayed the rope around a projection and, by gesture and shout, coached Maury along the route.

Maury, and then Doug, crossed without trouble.

Cal then led the way up the second chimney, wider than the first and deeper. This took them up another forty-odd feet to a ledge on which all three men could stand or sit together.

Cal was still not winded. But looking at the other two, he saw that Maury was damp-faced behind the faceplate of his mask. The older man’s breath was whistling in the respirator. It was time, thought Cal, to lighten loads. He had never expected to get far with some of their equipment in any case, but he had wanted the psychological advantage of starting the others out with everything needful.

“Maury,” he said, “I think we’ll leave your sidearm here, and some of the other stuff you’re carrying.”

“I can carry it,” said Maury. “I don’t need special favors.”

“No,” said Cal. “You’ll leave it. I’m the judge of what’s ahead of us, and in my opinion the time to leave it’s now.” He helped Maury off with most of what he carried, with the exception of a pup tent, his climbing tools and the water container and field rations. Then as soon as Maury was rested, they tackled the first of the two really difficult stretches of the cliff.

This was a ten-foot traverse that any experienced climber would not have found worrisome. To amateurs like themselves it was spine-chilling.

The route to be taken was to the left and up to a large, flat piece of rock wedged in a wide crack running diagonally up the rock face almost to its top. There were plenty of available footrests and handholds along the way. What would bother them was the fact that the path they had to take was around a boss, or protuberance of rock. To get around the boss it was necessary to move out over the empty atmosphere of a clear drop to the talus slope below.

Cal went first.

He made his way slowly but carefully around the outcurve of the rock, driving in one of his homemade pitons and attaching an equally homemade snap-ring to it, at the outermost point in the traverse. Passing the line that connected him to Maury through this, he had a means of holding the other men to the cliff if their holds should slip and they have to depend on the rope on their way around. The snap-ring and piton were also a psychological assurance.

Arrived at the rock slab in the far crack, out of sight of the other two, Cal belayed the rope and gave two tugs. A second later a tug came back. Maury had started crossing the traverse.

He was slow, very slow, about it. After agonizing minutes Cal saw Maury’s hand come around the edge of the boss. Slowly he passed the projecting rock to the rock slab. His face was pale and rigid when he got to where Cal stood. His breath came in short, quick pants.

Cal signaled on the rope again. In considerably less time than Maury had taken Doug came around the boss. There was a curious look on his face.

“What is it?” asked Cal.

Doug glanced back the way he had come. “Nothing, I guess,” he said. “I just thought I saw something moving back there. Just before I went around the corner. Something I couldn’t make out.”

Cal stepped to the edge of the rock slab and looked as far back around the boss as he could. But the ledge they had come from was out of sight. He stepped back to the ledge.

“Well,” he said to the others, “the next stretch is easier.”

VI

It was. The crack up which they climbed now slanted to the right at an almost comfortable angle.

They went up it using hands and feet like climbing a ladder. But if it was easy, it was also long, covering better than a hundred feet of vertical rock face. At the top, where the crack pinched out, there was the second tricky traverse across the rock face, of some eight feet. Then a short climb up a cleft and they stood together on top of the ridge.

Down below, they had been hidden by the mountain walls from the high winds above. Now for the first time, as they emerged onto the ridge they faced and felt them.

The warmsuits cut out the chill of the atmosphere whistling down on them from the mountain peak, but they could feel the pressure of it molding the suits to their bodies. They stood now once more in sunlight. Behind them they could see the hanging valley and the Harrier. Ahead was a cwm, a hollow in the steep mountainside that they would have to cross to get to a further ridge leading up to the mountain peak. Beyond and below the further ridge, they could see the far, sloping side of the mountain and, black against it, the tiny, oil-drum-end fragment of alien ship with a dot of white just outside it.

“We’ll stay roped,” said Cal. He pointed across the steep-sloping hollow they would need to cross to reach the further rocky ridge. The hollow seemed merely a tilted area with occasional large rock chunks perched on it at angles that to Earth eyes seemed to defy gravity. But there was a high shine where the sun’s rays struck.

“Is that ice?” said Maury, shading his eyes.

“Patches of it. A thin coating over the rocks,” said Cal. “It’s time to put on the crampons.”

They sat down and attached the metal frameworks to their boots that provided them with spiked footing. They drank sparingly of the water they carried and ate some of their rations. Cal glanced at the descending sun, and the blue-black sky above them. They would have several hours yet to cross the cwm, in daylight. He gave the order to go, and led off.

He moved carefully out across the hollow, cutting or kicking footholds in patches of ice he could not avoid. The slope was like a steep roof. As they approached the deeper center of the cwm, the wind from above seemed to be funnelled at them so that it was like a hand threatening to push them into a fall.

Some of the rock chunks they passed were as large as small houses. It was possible to shelter from the wind in their lees. At the same time, they often hid the other two from Cal’s sight, and this bothered him. He would have preferred to be able to watch them in their crossings of the ice patches, so that if one of them started to slide he would be prepared to belay the rope. As it was, in the constant moan and howl of the wind, his first warning would be the sudden strain on the rope itself. And if one of them fell and pulled the other off the mountainside, their double weight could drag Cal loose.

Not for the first time, Cal wished that the respirator masks they wore had been equipped with radio intercom. But these were not and there had been no equipment aboard the Harrier to convert them.

They were a little more than halfway across when Cal felt a tugging on the line.

He looked back. Maury was waving him up into a shelter of one of the big rocks. He waved back and turned off from the direct path, crawling up into the ice-free overhang. Behind him, as he turned, he saw Maury coming toward him, and behind Maury, Doug.

“Doug wants to tell you something!” Maury shouted against the wind noise, putting his mask up close to Cal’s.

“What is it?” Cal shouted.

“—Saw it again!” came Doug’s answer.

“Something moving?” Doug nodded. “Behind us?” Doug’s mask rose and fell again in agreement “Was it one of the aliens?”

“I think so!” shouted Doug. “It could be some sort of animal. It was moving awfully fast—I just got a glimpse of it!”

“Was it—” Doug shoved his masked face closer, and Cal raised his voice—“was it wearing any kind of clothing that you could see?”

“No!” Doug’s head shook back and forth.

“What kind of life could climb around up here without freezing to death—unless it had some protection?” shouted Maury to them both.

“We don’t know!” Cal answered. “Let’s not take chances. If it is an alien, he’s got all the natural advantages. Don’t take chances. You’ve got your gun, Doug. Shoot anything you see moving!”

Doug grinned and looked harshly at Cal from inside his mask.

“Don’t worry about me!” he shouted back. “Maury’s the one without a gun.”

“We’ll both keep an eye on Maury! Let’s get going now. There’s only about another hour or so before the sun goes behind those other mountains—and we want to be in camp underneath the far ridge before dark!”

He led off again and the other two followed.

As they approached the far ridge, the wind seemed to lessen somewhat. This was what Cal had been hoping for—that the far ridge would give them some protection from the assault of the atmosphere they had been enduring in the open. The dark wall of the ridge, some twenty or thirty feet in sudden height at the edge of the cwm, was now only a hundred yards or so away. It was already in shadow from the descending sun, as were the downslope sides of the big rock chunks. Long shadows stretched toward a far precipice edge where the cwm ended, several thousand feet below. But the open icy spaces were now ruddy and brilliant with the late sunlight. Cal thought wearily of the pup tents and his sleeping bag.

Without warning a frantic tugging on the rope roused him. He jerked around, and saw Maury, less than fifteen feet behind him, gesturing back the way they had come. Behind Maury, the rope to Doug led out of sight around the base of one of the rock chunks.

Then suddenly Doug slid into view.

Automatically Cal’s leg muscles spasmed tight, to take the sudden jerk of the rope when Doug’s falling body should draw it taut. But the jerk never came.

Sliding, falling, gaining speed as he descended the rooftop-steep slope of the cwm, Doug’s body no longer had the rope attached to it. The rope still lay limp on the ground behind Maury. And then Cal saw something he had not seen before. The dark shape of Doug was not falling like a man who finds himself sliding down two thousand feet to eternity. It was making no attempt to stop its slide at all. It fell limply, loosely, like a dead man—and indeed, just at that moment, it slid far upon a small, round boulder in his path which tossed it into the air like a stuffed dummy, arms and legs asprawl, and it came down indifferently upon the slope beyond and continued, gaining speed as it went.

Cal and Maury stood watching. There was nothing else they could do. They saw the dark shape speeding on and on, until finally it was lost for good among the darker shapes of the boulders farther on down the cwm. They were left without knowing whether it came eventually to rest against some rock, or continued on at last to fall from the distant edge of the precipice to the green, unknown depth that was far below them.

After a little while Maury stopped looking. He turned and climbed on until he had caught up with Cal. His eyes were accusing as he pulled in the loose rope to which Doug had been attached. They looked at it together.

The rope’s end had been cut as cleanly as any knife could have cut it.

The sun was just touching the further mountains. They turned without speaking and climbed on to the foot of the ridge wall.

Here the rocks were free of ice. They set up a single pup tent and crawled into it with their sleeping bags together, as the sun went down and darkness flooded their barren and howling perch on the mountainside.

VII

They took turns sitting up in their sleeping bags, in the darkness of their tiny tent, with Cal’s gun ready in hand.

Lying there in the darkness, staring at the invisible tent roof nine inches above his nose, Cal recognized that in theory the aliens could simply be better than humans—and that was that. But, Cal, being the unique sort of man he was, found that he could not believe such theory.

And so, being the unique sort of man he was, he discarded it. He made a mental note to go on trying to puzzle out the alien’s vulnerability tomorrow… and closing his eyes, fell into a light doze that was the best to be managed in the way of sleep.

When dawn began to lighten the walls of their tent they managed, with soup powder, a little of their precious water and a chemical thermal unit, to make some hot soup and get it into them. It was amazing what a difference this made, after the long, watchful and practically sleepless night. They put some of their concentrated dry rations into their stomachs on top of the soup and Cal unpacked and set up the small portable still.

He took the gun and his ice-hammer and crawled outside the tent. In the dawnlight and the tearing wind he sought ice which they could melt and then distill to replenish their containers of drinking water. But the only ice to be seen within any reasonable distance of their tent was the thin ice-glaze—verglas, mountaineers back on Earth called it—over which they had struggled in crossing the cwm the day before. And Cal dared not take their only gun too far from Maury, in case the alien made a sudden attack on the tent.

There was more than comradeship involved. Alone, Cal knew, there would indeed be no hope of his getting the Messenger to the mountaintop. Not even the alien could do that job alone—and so the alien’s strategy must be to frustrate the human party’s attempt to send a message.

It could not be doubted that the alien realized what their reason was for trying to climb the mountain. A race whose spaceships made use of the principle of no-time in their drives, who was equipped for war, and who responded to attack with the similarities shown so far, would not have a hard time figuring out why the human party was carrying the equipment on Cal’s pack up the side of a mountain.

More, the alien, had he had a companion, would probably have been trying to get message equipment of his own up into favorable dispatching position. Lacking a companion his plan must be to frustrate the human effort. That put the humans at an additional disadvantage. They were the defenders, and could only wait for the attacker to choose the time and place of his attempt against them.

And it would not have to be too successful an attempt, at that. It would not be necessary to kill either Cal or Maury, now that Doug was gone. To cripple one of them enough so that he could not climb and help his companion climb, would be enough. In fact, if one of them were crippled Cal doubted even that they could make it back to the Harrier. The alien then could pick them off at leisure.

Engrossed in his thoughts, half-deafened by the ceaseless wind, Cal woke suddenly to the vibration of something thundering down on him.

He jerked his head to stare upslope—and scrambled for his life. It was like a dream, with everything in slow motion—and one large chunk of rock with its small host of lesser rocks roaring down upon him.

Then—somehow—he was clear. The miniature avalanche went crashing by him, growing to a steady roar as it grew in size sweeping down alongside the ridge. Cal found himself at the tent, from which Maury was half-emerged, on hands and knees, staring down at the avalanche.

Cal swore at himself. It was something he had been told, and had forgotten. Such places as they had camped in last night were natural funnels for avalanches of loose rock. So, he remembered now, were wide cracks like the sloping one in the cliff face they had climbed up yesterday—as, indeed, the cwm itself was on a large scale. And they had crossed the cwm in late afternoon, when the heat of the day would have been most likely to loosen the frost that held precariously balanced rocks in place.

Only fool luck had gotten them this far!

“Load up!” he shouted to Maury. “We’ve got to get out of here.”

Maury had already seen that for himself. They left the pup-tent standing. The tent in Cal’s load would do. With that, the Messenger, their climbing equipment, their sleeping bags and their food and water, they began to climb the steeply sloping wall of the ridge below which they had camped. Before they were halfway up it, another large rock with its attendant avalanche of lesser rocks came by below them.

Whether the avalanches were alien-started, or the result of natural causes, made no difference now. They had learned their lesson the hard way. From now on, Cal vowed silently, they would stick to the bare and open ridges unless there was absolutely no alternative to entering avalanche territory. And only after every precaution.

In the beginning Cal had kept a fairly regular check on how Maury was doing behind him. But as the sun rose in the bluish-black of the high altitude sky overhead the weariness of his body seemed to creep into his mind and dull it. He still turned his head at regular intervals to see how Maury was doing. But sometimes he found himself sitting and staring at his companion without any real comprehension of why he should be watching over him.

The blazing furnace of K94 overhead, climbing toward its noontime zenith, contributed to this dullness of the mind. So did the ceaseless roaring of the wind which had long since deafened them beyond any attempt at speech. As the star overhead got higher in the sky this and the wind noise combined to produce something close to hallucinations… so that once he looked back and for a moment seemed to see the alien following them, not astraddle the ridge and hunching themselves forward as they were, but walking along the knife-edge of rock like a monkey along a branch, foot over foot, and grasping the rock with toes like fingers, oblivious of the wind and the sun.

Cal blinked and, the illusion—if that was what it was—was gone. But its image lingered in his brain with the glare of the sun and the roar of the wind.

His eyes had fallen into the habit of focusing on the rock only a dozen feet ahead of him. At last he lifted them and saw the ridge broaden, a black shadow lying sharply across it. They had come to the rock walls below the hanging glacier they had named the Hook.

They stopped to rest in the relative wind-break shelter of the first wall, then went on.

Considering the easiness of the climb they made remarkably slow progress. Cal slowly puzzled over this until, like the slow brightening of a candle, the idea grew in him to check the absolute altimeter at his belt

They were now nearly seven thousand feet higher up than they had been at the wreck of the Harrier. The mask respirators had been set to extract oxygen for them from the local atmosphere in accordance with the Harrier altitude. Pausing on a ledge, Cal adjusted his mask controls.

For a minute there seemed to be no difference at all. And then he began to come awake. His head cleared. He became sharply conscious, suddenly of where he stood—on a ledge of rock, surrounded by rock walls with, high overhead, the blue-black sky and brilliant sunlight on the higher walls. They were nearly at the foot of the third, and upper, battlement of the rock walls.

He looked over the edge at Maury, intending to signal the man to adjust his mask controls. Maury was not even looking up, a squat, lumpish figure in the warmsuit totally covered, with the black snout of the mask over his face. Cal tugged at the rope and the figure raised its face. Cal with his gloved hands made adjusting motions at the side of his mask. But the other’s face below, hidden in the shadow of the faceplate, stared up without apparent comprehension. Cal started to yell down to him—here the wind noise was lessened to the point where a voice might have carried—and then thought better of it.

Instead he tugged on the rope in the signal they had repeated an endless number of times; and the figure below, foreshortened to smallness stood dully for a moment and then began to climb. His eyes sharpened by the fresh increase in the oxygen flow provided by his mask Cal watched that slow climb almost with amazement carefully taking in the rope and belaying it as the other approached.

There was a heaviness, an awkwardness, about the warmsuited limbs, as slowly—but strongly enough—they pulled the climber up toward Cal. There was something abnormal about their movement. As the other drew closer, Cal stared more and more closely until at last the gloves of the climber fastened over the edge of the ledge.

Cal bent to help him. But, head down not looking, the other hoisted himself up alongside Cal and a little turned away.

Then in that last instant the combined flood of instinct and a lifetime of knowledge cried certainty. And Cal knew.

The warmsuited figure beside him was Maury no longer.

VIII

Reflexes have been the saving of many a man’s life. In this case, Cal had been all set to turn and climb again, the moment Maury stood beside him on the edge. Now recognizing that somewhere among these rocks, in the past fumbling hours of oxygen starvation, Maury had ceased to live and his place had been taken by the pursuing alien, Cal’s reflexes took over.

If the alien had attacked the moment he stood upright on the ledge, different reflexes would have locked Cal in physical combat with the enemy. When the alien did not attack, Cal turned instinctively to the second prepared response of his body and began automatically to climb to the next ledge.

There was no doubt that any other action by Cal, any hesitation, any curiosity about his companion would have forced the alien into an immediate attack. For then there would have been no reason not to attack. As he climbed, Cal felt his human brain beginning to work again after the hours of dullness. He had time to think.

His first thought was to cut the line that bound them together, leaving the alien below. But this would precipitate the attack Cal had already instinctively avoided. Any place Cal could climb at all, the alien could undoubtedly climb with ease. Cal’s mind chose and discarded possibilities. Suddenly he remembered the gun that hung innocently at his hip. With that recollection, the situation began to clear and settle in his mind. The gun evened things. The knowledge that it was the alien on the other end of the rope, along with the gun, more than evened things. Armed and prepared, he could afford to risk the present situation for a while. He could play a game of pretense as well as the alien could, he thought.

That amazing emotional center of gravity, Cal’s personal sense of security and adequacy that had so startled the psychology department at the university, was once more in command of the situation. Cal felt the impact of the question—why was the alien pretending to be Maury? Why had he adapted himself to man-shape, put on man’s clothes and fastened himself to the other end of Cal’s climbing rope?

Perhaps the alien desired to study the last human that opposed him before he tried to destroy it. Perhaps he had some hope of rescue by his own people, and wanted all the knowledge for them he could get. If so it was a wish that cut two ways. Cal would not be sorry of the chance to study a living alien in action.

And when the showdown came—there was the gun at Cal’s belt to offset the alien’s awesome physical natural advantage.

They continued to climb. Cal watched the other figure below him. What he saw was not reassuring.

With each wall climbed, the illusion of humanity grew stronger. The clumsiness Cal had noticed at first—the appearance of heaviness—began to disappear. It began to take on a smoothness and a strength that Maury had never shown in the climbing. It began in fact, to look almost familiar. Now Cal could see manlike hunching and bulgings of the shoulder muscles under the warmsuit’s shapelessness, as the alien climbed and a certain trick of throwing the head from right to left to keep a constant watch for a better route up the face of the rock wall.

It was what he did himself, Cal realized suddenly. The alien was watching Cal climb ahead of him and imitating even the smallest mannerisms of the human.

They were almost to the top of the battlements, climbing more and more in sunlight. K94 was already far down the slope of afternoon. Cal began to hear an increase in the wind noise as they drew close to the open area above. Up there was the tumbled rock-strewn ground of a terminal moraine and then the snow slope to the hook glacier.

Cal had planned to camp for the night above the moraine at the edge of the snow slope. Darkness was now only about an hour away and with darkness the showdown must come between himself and the alien. With the gun, Cal felt a fair amount of confidence. With the showdown, he would probably discover the reason for the alien’s impersonation of Maury.

Now Cal pulled himself up the last few feet. At the top of the final wall of the battlements the windblast was strong. Cal found himself wondering if the alien recognized the gun as a killing tool. The alien which had attacked them outside the Harrier had owned neither weapons nor clothing. Neither had the ones filmed as they fell from the enemy ship, or the one lying dead outside the fragment of that ship on the other side of the mountain. It might be that they were so used to their natural strength and adaptability they did not understand the use of portable weapons. Cal let his hand actually brush against the butt of the sidearm as the alien climbed on to the top of the wall and stood erect, faceplate turned a little from Cal.

But the alien did not attack.

Cal stared at the other for a long second, before turning and starting to lead the way through the terminal moraine, the rope still binding them together. The alien moved a little behind him, but enough to his left so that he was within Cal’s range of vision, and Cal was wholly within his. Threading his way among the rock rubble of the moraine, Cal cast a glance at the yellow orb of K94, now just hovering above the sharp peaks of neighboring mountains around them.

Night was close. The thought of spending the hours of darkness with the other roped to him cooled the back of Cal’s neck. Was it darkness the alien was waiting for?

Above them, as they crossed the moraine the setting sun struck blazing brilliance from the glacier and the snow slope. In a few more minutes Cal would have to stop to set up the puptent, if he hoped to have enough light to do so. For a moment the wild crazy hope of a notion crossed Cal’s mind that the alien had belatedly chosen life over duty. That at this late hour, he had changed his mind and was trying to make friends.

Cold logic washed the fantasy from Cal’s mind. This being trudging almost shoulder to shoulder with him was the same creature than had sent Doug’s limp and helpless body skidding and falling down the long ice-slope to the edge of an abyss. This companion alongside was the creature that had stalked Maury somewhere among the rocks of the mountainside and disposed of him, and stripped his clothing off and taken his place.

Moreover, this other was of the same race and kind as the alien who had clung to the hull of the falling Harrier and, instead of trying to save himself and get away on landing, had made a suicidal attack on the eight human survivors. The last thing that alien had done, when there was nothing else to be done, was to try to take as many humans as possible into death with him.

This member of the same race walking side by side with Cal would certainly do no less.

But why was he waiting so long to do it? Cal frowned hard inside his mask. That question had to be answered. Abruptly he stopped. They were through the big rubble of the moraine, onto a stretch of gravel and small rock. The sun was already partly out of sight behind the mountain peaks. Cal untied the rope and began to unload the pup tent.

Out of the corner of his eyes, he could see the alien imitating his actions. Together they got the tent set up and their sleeping bags inside. Cal crawled in the tiny tent and took off his boots. He felt the skin between his shoulder blades crawl as a second later the masked head of his companion poked itself through the tent opening and the other crept on hands and knees to the other sleeping bag. In the dimness of the tent with the last rays of K94 showing thinly through its walls, the shadow on the far tent wall was a monstrous parody of a man taking off his boots.

The sunlight failed and darkness filled the tent. The wind moaned loudly outside. Cal lay tense, his left hand gripping the gun he had withdrawn from its holster. But there was no movement.

The other had gotten into Maury’s sleeping bag and lay with his back to Cal. Facing that back, Cal slowly brought the gun to bear. The only safe thing to do was to shoot the alien now, before sleep put Cal completely at the other’s mercy.

Then the muzzle of the gun in Cal’s hand sank until it pointed to the fabric of the tent floor. To shoot was the only safe thing—and it was also the only impossible thing.

Ahead of them was the snow-field and the glacier, with its undoubted crevasses and traps hidden under untrustworthy caps of snow. Ahead of them was the final rock climb to the summit. From the beginning, Cal had known no one man could make this final stretch alone. Only two climbers roped together could hope to make it safely to the top.

Sudden understanding burst on Cal’s mind. He quietly reholstered the gun. Then, muttering to himself, he sat up suddenly without any attempt to hide the action, drew a storage cell lamp from his pack and lit it. In the sudden illumination that burst on the tent he found his boots and stowed them up alongside his bag.

He shut the light off and lay down again, feeling cool and clear-headed. He had had only a glimpse in turning, but the glimpse was enough. The alien had shoved Maury’s pack up into a far corner of the tent as far away from Cal as possible. But the main pockets of that pack now bulked and swelled as they had not since Cal had made Maury lighten his load on the first rock climb.

Cal lay still in the darkness with a grim feeling of humor inside him. Silently, in his own mind he took his hat off to his enemy. From the beginning he had assumed that the only possible aim one of the other race could have would be to frustrate the human attempt to get word back to the human base—so that neither race would know of the two ships’ encounter.

Cal had underestimated the other. And he should not have, for technologically they were so similar and equal. The aliens had used a no-time drive. Clearly, they had also had a no-time rescue signalling device like the Messenger, which needed to be operated from the mountaintop.

The alien had planned from the beginning to join the human effort to get up into Messenger-firing position, so as to get his own device up there.

He too, had realized—in spite of his awesome natural advantage over the humans—that no single individual could make the last stage of the climb alone. Two, roped together, would have a chance. He needed Cal as much as Cal needed him.

In the darkness, Cal almost laughed out loud with the irony of it. He need not be afraid of sleeping. The showdown would come only at the top of the mountain.

Cal patted the butt of the gun at his side and smiling, he fell asleep.

But he did not smile, the next morning when, on waking, he found the holster empty.

IX

When he awoke to sunlight through the tent walls the form beside him seemed not to have stirred, but the gun was gone.

As they broke camp, Cal looked carefully for it. But there was no sign of it either in the tent, or in the immediate vicinity of the camp. He ate some of the concentrated rations he carried and drank some of the water he still carried. He made a point not to look to see if the alien was imitating him. There was a chance, he thought, that the alien was still not sure whether Cal had discovered the replacement.

Cal wondered coldly where on the naked mountain-side Maury’s body might lie—and whether the other man had recognized the attacker who had killed him, or whether death had taken him unawares.

Almost at once they were on the glacier proper. The glare of ice was nearly blinding. Cal stopped and uncoiled the rope from around him. He tied himself on, and the alien in Maury’s warmsuit, without waiting for a signal, tied himself on also.

Cal went first across the ice surface, thrusting downward with the forearm-length handle of his homemade ice axe. When the handle penetrated only the few niches of top snow and jarred against solidity, he chipped footholds like a series of steps up the steep pitch of the slope. Slowly they worked their way forward.

Beyond the main length of the hook rose a sort of tower of rock that was the main peak. The tower appeared to have a cup-shaped area or depression in its center—an ideal launching spot for the Messenger, Cal had decided, looking at it through a powerful telescopic viewer from the wreck of the Harrier. A rare launching spot in this landscape of steeply tilted surfaces.

Without warning a shadow fell across Cal’s vision. He started and turned to see the alien towering over him. But, before he could move, the other had begun chipping at the ice higher up. He cut a step and moved up ahead of Cal. He went on, breaking trail, cutting steps for Cal to follow.

A perverse anger began to grow in Cal. He was aware of the superior strength of the other, but there was something contemptuous about the alien’s refusal to stop and offer Cal his turn. Cal moved up close behind the other and abruptly began chipping steps in a slightly different direction. As he chipped, he moved up them, and gradually the two of them climbed apart.

When the rope went taut between them they both paused and turned in each other’s direction—and without warning the world fell out from underneath Cal.

He felt himself plunging. The cruel and sudden jerk of the rope around his body brought him up short and he dangled, swaying between ice-blue walls.

He craned his head backward and looked up. Fifteen feet above him were two lips of snow, and behind these the blue-black sky. He looked down and saw the narrowing rift below him plunge down into darkness beyond vision.

For a moment his breath caught in his chest

Then there was a jerk on the rope around him, and he saw the wall he was facing drop perhaps eighteen inches. He had been lifted. The jerk came again, and again. Steadily it progressed. A strength greater than that of any human was drawing him up.

Slowly, jerk by jerk, Cal mounted to the edge of the crevasse—to the point where he could reach up and get his gloved hands on the lip of ice and snow, to the point where he could get his forearms out on the slope and help lift his weight from the crevasse.

With the aid of the rope he crawled out at last on the downslope side of the crevasse. Just below him, he saw the alien in Maury’s clothing, buried almost to his knees in loose snow, half kneeling, half-crouching on the slope with the rope in his grasp. The alien did not straighten up at once. It was as if even his great strength had been taxed to the utmost

Cal trembling stared at the other’s crouched immobility. It made sense. No physical creature was possessed of inexhaustible energy—and the alien had also been climbing a mountain. But, the thought came to chill Cal’s sudden hope, if the alien had been weakened, Cal had been weakened also. They stood in the same relationship to each other physically that they had to begin with.

After a couple of minutes, Cal straightened up. The alien straightened up also, and began to move. He stepped out and took the lead off to his left, circling around the crevasse revealed by Cal’s fall. He circled wide, testing the surface before him.

They were nearing the bend of the hook—the point at which they could leave the glacier for the short slope of bare rock leading up to the tower of the main peak and the cup-shaped spot from which Cal had planned to send off the Messenger. The hook curved to their left. Its outer bulge reached to the edge of a ridge on their right running up to the main peak, so that there was no avoiding a crossing of this final curve of the glacier. They had been moving closer to the ice-edge of the right-hand ridge, and now they were close enough to see how it dropped sheer, a frightening distance to rocky slopes far below.

The alien, leading the way, had found and circled a number of suspicious spots in the glacier ice. He was now a slack thirty feet of line in front of Cal, and some fifty feet from the ice-edge of the rim.

Suddenly, with almost no noise—as if it had been a sort of monster conjuring feat—the whole edge of the ice disappeared.

The alien and Cal both froze in position.

Cal, ice axe automatically dug in to anchor the other, was still on what seemed to be solid ice-covered rock. But the alien was revealed to be on an ice-bridge, all that was left of what must have been a shelf of glacier overhanging the edge of the rocky ridge. The rock was visible now—inside the alien’s position. The ice-bridge stretched across a circular gap in the edge of the glacier, to ice-covered rock at the edge of the gap ahead and behind. It was only a few feet thick and the sun glinted on it.

Slowly, carefully, the masked and hidden face of the alien turned to look back at Cal, and the darkness behind his faceplate looked square into Cal’s eyes.

For the first time there was direct communication between them. The situation was their translator and there was no doubt between them about the meanings of their conversation. The alien’s ice-bridge might give way at any second. The jerk of the alien’s fall on the rope would be more than the insecure anchor of Cal’s ice-hammer could resist. If the alien fell while Cal was still roped to him, they would both go.

On the other hand, Cal could cut himself loose. Then, if the ice-bridge gave way, Cal would have lost any real chance of making the peak. But he would still be alive.

The alien made no gesture asking for help. He merely looked.

Well, which is it to be? the darkness behind his faceplate asked. If Cal should cut loose, there was only one thing for the alien to do, and that was to try to crawl on across the ice-bridge on his own—an attempt almost certain to be disastrous.

Cal felt a cramping in his jaw muscles. Only then did he realize he was smiling—a tight-lipped, sardonic smile. Careful not to tauten the rope between them, he turned and picked up the ice axe, then drove it into the ice beyond and to his left. Working step by step, from anchor point to anchor point, he made his way carefully around the gap, swinging well inside it, to a point above the upper end of the ice-bridge. Here he hammered and cut deeply into the ice until he stood braced in a two-foot hole with his feet flat against a vertical wall, lying directly back against the pull of the rope leading to the alien.

The alien had followed Cal’s movements with his gaze. Now, as he saw Cal bracing himself, the alien moved forward and Cal took up the slack in the rope between them. Slowly, carefully, on hands and knees like a cat stalking in slow motion a resting butterfly, the alien began to move forward across the ice-bridge.

One foot—two feet—and the alien froze suddenly as a section of the bridge broke out behind him.

Now there was no way to go but forward. Squinting over the lower edge of his faceplate and sweating in his warmsuit, Cal saw the other move forward again. There were less than ten feet to go to solid surface. Slowly, the alien crept forward. He had only five feet to go, only four, only three—

The ice-bridge went out from under him.

X

The shock threatened to wrench Cal’s arms from their shoulder-sockets—but skittering, clawing forward like a cat in high gear, the alien was snatching at the edge of the solid ice. Cal suddenly gathered in the little slack in the line and threw his weight into the effort of drawing the alien forward.

Suddenly the other was safe, on solid surface. Quickly, without waiting, Cal began to climb.

He did not dare glance down to see what the alien was doing; but from occasional tautenings of the rope around his shoulders and chest, he knew that the other was still tied to him. This was important, for it meant that the moment of their showdown was not yet. Cal was gambling that the other, perhaps secure in the knowledge of his strength and his ability to adapt, had not studied the face of this tower as Cal had studied it through the telescopic viewer from the Harrier.

From that study, Cal had realized that it was a face that he himself might be able to climb unaided. And that meant a face that the alien certainly could climb unaided. If the alien should realize this, a simple jerk on the rope that was tied around Cal would settle the problem of the alien as far as human competition went. Cal would be plucked from his meager hand and footholds like a kitten from the back of a chair, and the slope below would dispose of him. He sweated now, climbing, trying to remember the path up the towerside as he had planned it out, from handhold to handhold, gazing through the long-distance viewer.

He drew closer to the top. For some seconds and minutes now, the rope below him had been completely slack. He dared not look down to see what that might mean. Then finally he saw the edge of the cup-shaped depression above him, bulging out a little from the wall.

A second more and his fingers closed on it. Now at last he had a firm handhold. Quickly he pulled himself up and over the edge. For a second perspiration blurred his vision. Then he saw the little, saucer sloping amphitheater not more than eighteen feet wide, and the further walls of the tower enclosing it on three sides.

Into the little depression the light of K94 blazed from the nearly black sky. Unsteadily Cal got to his feet and turned around. He looked down the wall he had just climbed.

The alien still stood at the foot of the wall. He had braced himself there, evidently to belay Cal against a fall that would send him skidding down the rock slope below. Though what use to belay a dead man, Cal could not understand, since the more than thirty feet of fall would undoubtedly have killed him. Now, seeing Cal upright and in solid position, the alien put his hands out toward the tower wall as if he would start to climb.

Cal immediately hauled taut on the line, drew a knife from his belt and, reaching as far down as possible, cut the line.

The rope end fell in coils at the alien’s feet. The alien was still staring upward as Cal turned and went as quickly as he could to the center of the cup-shaped depression.

The wind had all but died. In the semi-enclosed rock depression the reflected radiation of the star overhead made it hot. Cal unsnapped his pack and let it drop. He stripped off the gloves of his warmsuit and, kneeling, began to open up the pack. His ears were alert. He heard nothing from outside the tower, but he knew that he had minutes at most.

He laid out the three sections of the silver-plated Messenger, and began to screw them together. The metal was warm to his touch after being in the sun-warmed backpack, and his fingers, stiff and cramped from gripping at handholds, fumbled. He forced himself to move slowly, methodically, to concentrate on the work at hand and forget the alien now climbing the tower wall with a swiftness no human could have matched.

Cal screwed the computer-message-beacon section of the nose tight to the drive section of the middle. He reached for the propulsive unit that was the third section. It rolled out of his hand. He grabbed it up and began screwing it on to the two connected sections.

The three support legs were still in the pack. He got the first one out and screwed it on. The next stuck for a moment, but he got it connected. His ear seemed to catch a scratching noise from the outside of the tower where the alien would be climbing. He dug in the bag, came out with the third leg and screwed it in. Sweat ran into his eyes inside the mask faceplate, and he blinked to clear his vision.

He set the Messenger upright on its three legs. He bent over on his knees, facemask almost scraping the ground to check the level indicator.

Now he was sure he heard a sound outside on the wall of the tower. The leftmost leg was too long. He shortened it. Now the middle leg was off. He lengthened that. He shortened the leftmost leg again… slowly… there, the Messenger was leveled.

He glanced at the chronometer on his wrist. He had set it with the ship’s chronometer before leaving. Sixty-six ship’s hours thirteen minutes, and… the sweep second hand was moving. He fumbled with two fingers in the breast pocket of his warmsuit, felt the small booklet he had made up before leaving and pulled it out. He flipped through the pages of settings, a row of them for each second of time. Here they were… sixty-three hours, thirteen minutes—

A gust of wind nipped the tiny booklet from his stiffened fingers. It fluttered across the floor of the cup and into a crack in the rock wall to his right. On hands and knees he scrambled after it, coming up against the rock wall with a bang.

The crack reached all the way through the further wall, narrowing until it was barely wide enough for daylight to enter—or a booklet to exit. The booklet was caught crossways against the unevenness of the rock sides. He reached in at arm’s length. His fingers touched it. They shoved it a fraction of an inch further away. Sweat rolled down his face.

He ground the thickness of his upper arm against the aperture of the crack. Gently, gently, he maneuvered two fingers into position over the near edge of the booklet. The fingers closed. He felt it. He pulled back gently. The booklet came.

He pulled it out

He was back at the Messenger in a moment, finding his place in the pages again. Sixteen hours—fourteen minutes—the computer would take four minutes to warm and fire the propulsive unit.

A loud scratching noise just below the lip of the depression distracted him for a second.

He checked his chronometer. Sixty-three hours, sixteen minutes plus… moving on toward thirty seconds. Make it sixty-three hours sixteen minutes even. Setting for sixty-three hours, sixteen minutes plus four minutes—sixty-three hours, twenty minutes.

His fingers made the settings on the computer section as the second hand of his chronometer crawled toward the even minute…

There.

His finger activated the computer. The Messenger began to hum faintly, with a soft internal vibration.

The sound of scraping against rock was right at the lip of the depression, but out of sight.

He stood up. Four minutes the Messenger must remain undisturbed. Rapidly, but forcing himself to calmness, he unwound the rest of the rope from about him and unclipped it. He was facing the lip of the depression over which the alien would come, but as yet there was no sign. Cal could not risk the time to step to the depression’s edge and make sure.

The alien would not be like a human being, to be dislodged by a push as he crawled over the edge of the lip. He would come adapted and prepared. As quickly as he could without fumbling, Cal fashioned a slipknot in one end of the rope that hung from his waist.

A gray, wide, flat parody of a hand slapped itself over the lip of rock and began to change form even as Cal looked. Cal made a running loop in his rope and looked upward. There was a projection of rock in the ascending walls on the far side of the depression that would do. He tossed his loop up fifteen feet toward the projection. It slipped off—as another hand joined the first on the lip of rock. The knuckles were becoming pale under the pressure of the alien’s great weight

Cal tossed the loop again. It caught. He drew it taut.

He backed off across the depression, out of line with the Messenger, and climbed a few feet up the opposite wall. He pulled the rope taut and clung to it with desperate determination.

And a snarling tiger’s mask heaved itself into sight over the edge of rock, a tiger body following. Cal gathered his legs under him and pushed off. He swung out and downward, flashing toward the emerging alien, and they slammed together, body against fantastic body.

For a fraction of a second they hung together, toppling over space while the alien’s lower extremities snatched and clung to the edge of rock.

Then the alien’s hold loosened. And wrapped together, still struggling, they fell out and down toward the rock below accompanied by a cascade of rocks.

XI

“Waking in a hospital,” Cal said later, “when you don’t expect to wake at all, has certain humbling effects.”

It was quite an admission for someone like himself, who had by his very nature omitted much speculation on either humbleness or arrogance before. He went deeper into the subject with Joe Aspinall when the Survey Team Leader visited him in that same hospital back on Earth. Joe by this time, with a cane, was quite ambulatory.

“You see,” Cal said, as Joe sat by the hospital bed in which Cal lay, with the friendly and familiar sun of Earth making the white room light about them, “I got to the point of admiring that alien—almost of liking him. After all, he saved my life, and I saved his. That made us close, in a way. Somehow, now that I’ve been opened up to include creatures like him, I seem to feel closer to the rest of my own human race. You understand me?”

“I don’t think so,” said Joe.

“I mean, I needed that alien. The fact brings me to think that I may need the rest of you, after all. I never really believed I did before. It made things lonely.”

“I can understand that part of it,” said Joe.

“That’s why,” said Cal, thoughtfully, “I hated to kill him, even if I thought I was killing myself at the same time.”

“Who? The alien?” said Joe. “Didn’t they tell you? You didn’t kill him.”

Cal turned his head and stared at his visitor.

“No, you didn’t kill him!” said Joe. “When the rescue ship came they found you on top of him and both of you halfway down that rock slope. Evidently landing on top of him saved you. Just his own natural toughness saved him—that and being able to spread himself out like a rug and slow his fall. He got half a dozen broken bones—but he’s alive right now.”

Cal smiled. “I’ll have to go say hello to him when I get out of here.”

“I don’t think they’ll let you do that,” said Joe. “They’ve got him guarded ten deep someplace. Remember, his people still represent a danger to the human race greater than anything we’ve ever run into.”

“Danger?” said Cal. “They’re no danger to us.”

It was Joe who stared at this. “They’ve got a definite weakness,” said Cal. “I figured they must have. They seemed too good to be true from the start. It was only in trying to beat him out to the top of the mountain and get the Messenger off that I figured out what it had to be, though.”

“What weakness? People’ll want to hear about this!” said Joe.

“Why, just what you might expect,” said Cal. “You don’t get something without giving something away. What his race had gotten was the power to adapt to any situation. Their weakness is that same power to adapt.”

“What’re you talking about?”

“I’m talking about my alien friend on the mountain,” said Cal, a little sadly. “How do you suppose I got the Messenger off? He and I both knew we were headed for a showdown when we reached the top of the mountain. And he had the natural advantage of being able to adapt. I was no match for him physically. I had to find some advantage to outweigh that advantage of his. I found an instinctive one.”

“Instinctive…” said Joe, looking at the big, bandaged man under the covers and wondering whether he ought not to ring for the nurse.

“Of course, instinctive,” said Cal thoughtfully, staring at the bed sheet. “His instincts and mine were diametrically opposed. He adapted to fit the situation. I belonged to a people who adapted situations to fit them. I couldn’t fight a tiger with my bare hands, but I could fight something half-tiger, half something else.”

“I think I’ll just ring for the nurse,” said Joe, leaning forward to the button on the bedside table.

“Leave that alone,” said Cal calmly. “It’s simple enough. What I had to do was force him into a situation where he would be between adaptations. Remember, he was as exhausted as I was, in his own way; and not prepared to quickly understand the unexpected.”

“What unexpected?” Joe gaped at him. “You talk as if you thought you were in control of the situation all the way.”

“Most of the way,” said Cal. “I knew we were due to have a showdown. I was afraid we’d have it at the foot of the tower—but he was waiting until we were solidly at the top. So I made sure to get up to that flat spot in the tower first, and cut the rope. He had to come up the tower by himself.”

“Which he was very able to do.”

“Certainly—in one form. He was in one form coming up,” said Cal. “He changed to his fighting form as he came over the edge—and those changes took energy. Physical and nervous, if not emotional energy, when he was pretty exhausted already. Then I swung at him like Tarzan as he was balanced, coming over the edge of the depression in the rock.”

“And had the luck to knock him off,” said Joe. “Don’t tell me with someone as powerful as that it was anything but luck. I was there when Mike and Sam got killed at the Harrier, remember.”

“Not luck at all,” said Cal, quietly. “A foregone conclusion. As I say, I’d figured out the balance sheet for the power of adaptation. It had to be instinctive. That meant that if he was threatened, his adaptation to meet the threat would take place whether consciously he wanted it to or not. He was barely into tiger-shape, barely over the edge of the cliff, when I hit him and threatened to knock him off into thin air. He couldn’t help himself. He adapted.”

“Adapted!” said Joe, staring.

“Tried to adapt—to a form that would enable him to cling to his perch. That took the strength out of his tiger-fighting form, and I was able to get us both off the cliff together instead of being torn apart the minute I hit him. The minute we started to fall, he instinctively spread out and stopped fighting me altogether.”

Joe sat back in his chair. After a moment, he swore.

“And you’re just now telling me this?” he said.

Cal smiled a little wryly.

“I’m surprised you’re surprised,” he said. “I’d thought people back here would have figured all this out by now. This character and his people can’t ever pose any real threat to us. For all their strength and slipperiness, their reaction to life is passive. They adapt to it. Ours is active—we adapt it to us. On the instinctive level, we can always choose the battlefield and the weapons, and win every time in a contest.”

He stopped speaking and gazed at Joe, who shook his head slowly.

“Cal,” said Joe at last, “you don’t think like the rest of us.”

Cal frowned. A cloud passing beyond the window dimmed the light that had shone upon him.

“I’m afraid you’re right,” he said quietly. “For just a while, I had hopes it wasn’t so.”