The pilot made an examination down the floor-plate hole, with a flashlight to see by and two mirrors to show him the contents of a spot he could not possibly reach with any instrument. Joe heard his report, made to the ground by radio.

“It’s a grenade,” he said coldly. “It took time to fix it the way it is. At a guess, the ship was booby-trapped at the time of its last overhaul. But it was arranged that the booby trap had to be set, the trigger cocked, by somebody doing something very simple at a different place and later on. We’ve been flying with that grenade in the wheel well for two weeks. But it was out of sight. Today, back at the airfield, a sandy-haired man reached up and pulled a string he knew how to find. That loosened a slipknot. The grenade rolled down to a new position. Now when the wheel goes down the pin is pulled. You can figure things out from that.”

It was an excellent sabotage device. If a ship blew up two weeks after overhaul, it would not be guessed that the bomb had been placed so long before. Every search would be made for a recent opportunity for the bomb’s placing. A man who merely reached in and pulled a string that armed the bomb and made it ready for firing would never be suspected. There might be dozens of planes, now carrying their own destruction about with them.

The pilot said into the microphone: “Probably....” He listened. “Very well, sir.”

He turned away and nodded to the co-pilot, now savagely keeping the ship in wide, sweeping circles, the rims of which barely touched the farthermost corner of the airport on the ground below.

“We’ve authority to jump,” he said briefly. “You know where the chutes are. But there is a chance I can belly-land without that grenade blowing. I’m going to try that.”

The co-pilot said angrily: “I’ll get him a chute.” He indicated Joe, and said furiously, “They’ve been known to try two or three tricks, just to make sure. Ask if we should dump cargo before we crash-land!”

The pilot held up the microphone again. He spoke. He listened.

“Okay to dump stuff to lighten ship.”

“You won’t dump my crates,” snapped Joe. “And I’m staying to see you don’t! If you can ride this ship down, so can I!”

The co-pilot got up and scowled at him.

“Anything I can move out, goes. Will you help?”

Joe followed him through the door into the cargo compartment.

The space there was very considerable, and bitterly cold. The crates from the Kenmore plant were the heaviest items of cargo. Other objects were smaller. The co-pilot made his way to the rear and pulled a lever. Great, curved doors opened at the back of the plane. Instantly there was such a bellowing of motors that all speech was impossible. The co-pilot pulled out a clip of colored-paper slips and checked one with the nearest movable parcel. He painstakingly made a check mark and began to push the box toward the doors.

It was not a conspicuously sane operation. So near the ground, the plane tended to waver. The air was distinctly bumpy. To push a massive box out a doorway, so it would tumble down a thousand feet to desert sands, was not so safe a matter as would let it become tedious. But Joe helped. They got the box to the door and shoved it out. It went spinning down. The co-pilot hung onto the doorframe and watched it land. He chose another box. He checked it. And another. Joe helped. They got them out of the door and dropping dizzily through emptiness. The plane soared on in circles. The desert, as seen through the opened clamshell doors, reeled away astern, and then seemed to tilt, and reeled away again. Joe and the co-pilot labored furiously. But the co-pilot checked each item before he jettisoned it.

It was a singularly deliberate way to dump cargo to destruction. A metal-bound box. Over the edge of the cargo space floor. A piece of machinery, visible through its crate. A box marked Instruments. Fragile. Each one checked off. Each one dumped to drop a thousand feet or more. A small crated dynamo. This item and that. A crate marked Stationery. It would be printed forms for the timekeepers, perhaps. But it wasn’t.

It dropped out. The plane bellowed on. And suddenly there was a burst of blue-white flame on the desert below. The box that should have contained timecards had contained something very much more explosive. As the plane roared on—rocking from the shock wave of the explosion—Joe saw a crater and a boiling cloud of smoke and flying sand.

The co-pilot spoke explosively and furiously, in the blasting uproar of the motors. He vengefully marked the waybill of the parcel that had exploded. But then they went back to the job of dumping cargo. They worked well as a team now. In no more than minutes everything was out except the four crates that were the gyros. The co-pilot regarded them dourly, and Joe clenched his fists. The co-pilot closed the clamshell doors, and it became possible to hear oneself think again.

“Ship’s lighter, anyhow,” reported the co-pilot, back in the cabin. “Tell ’em this is what exploded.”

The pilot took the slip. He plucked down the microphone—exactly like somebody picking up an interoffice telephone—and reported the waybill number and description of the case that had been an extra bomb. The ship carrying the pilot gyros had been booby-trapped—probably with a number of other ships—and a bomb had been shipped on it, and a special saboteur with a private plane had shot at it with rockets. The pilot gyros were critical devices. They had to be on board the Platform when it took off, and they took months to make and balance. There had been extra pains taken to prevent their arrival!

“I’m dumping gas now,” said the pilot into the microphone, “and then coming in for a belly landing.”

The ship flew straightaway. It flew more lightly, and it bounced a little. When gas is dumped one has to slow to not more than one hundred and seventy-five knots and fly level. Then one is supposed to fly five minutes after dumping with the chutes in the drain position—and even then there is forty-five minutes of flying fuel still in the tanks.

The ship swept around and headed back for the now far-distant field. It went slowly lower and lower and lower until it seemed barely to skim the minor irregularities in the ground. And low like this, the effect of speed was terrific.

The co-pilot thought of something. Quickly he went back into the cargo space. He returned with an armful of blankets. He dumped them on the floor.

“If that grenade does go!” he said sourly.

Joe helped. In the few minutes before Bootstrap loomed near, they filled the bottom of the cabin with blankets. Especially around the pilots’ chairs. And there was a mound of blanketing above the actual place where the grenade might be. It made sense. Soft stuff like blankets would absorb an explosion better than anything else. But the pilot thought the grenade might not blow.

“Hold fast!” snapped the pilot.

The wing flaps were down. That slowed the ship a little. It had been lightened. That helped. They went in over the edge of the field less than man-height high. Joe found his hands closing convulsively on a handgrip. He saw a crash wagon starting out from the side of the runway. A fire truck started for the line the plane followed.

Four feet above the rushing sand. Three. The pilot eased back the stick. His face was craggy and very grim and very hard. The ship’s tail went down and dragged. It bumped. Then the plane careened and slid and half-whirled crazily, and then the world seemed to come to an end. Crashes. Bangs. Shrieks of torn metal. Bumps, thumps and grindings. Then a roaring.

Joe pulled himself loose from where he had been flung—it seemed to him that he peeled himself loose—and found the pilot struggling up, and he grabbed him to help, and the co-pilot hauled at them both, and abruptly all three of them were in the open air and running at full speed away from the ship.

The roar abruptly became a bellowing. There was an explosion. Flames sprouted everywhere. The three men ran stumblingly. But even as they ran, the co-pilot swore.

“We left something!” he panted.

Joe heard a crescendo of booming, crackling noises behind. Something else exploded dully. But he should be far enough away by now.

He turned to look, and he saw blackening wreckage immersed in roaring flames. The flames were monstrous. They rose sky-high, it seemed—more flames than forty-five minutes of gasoline should have produced. As he looked, something blew up shatteringly, and fire raged even more furiously. Of course in such heat the delicately adjusted gyros would be warped and ruined even if the crash hadn’t wrecked them beforehand. Joe made thick, incoherent sounds of rage.

The plane was now an incomplete, twisted skeleton, licked through by flames. The crash wagon roared to a stop beside them.

“Anybody hurt? Anybody left inside?”

Joe shook his head, unable to speak for despairing rage. The fog wagon roared up, already spouting mist from its nozzles. Its tanks contained water treated with detergent so that it broke into the finest of droplets when sprayed at four hundred pounds pressure. It drenched the burning wreck with that heavy mist, in which a man would drown. No fire could possibly sustain itself. In seconds, it seemed, there were only steam and white vapor and fumes of smoldering substances that gradually lessened.

But then there was a roaring of motorcycles racing across the field with a black car trailing them. The car pulled up beside the fog wagon, then sped swiftly to where Joe was coming out of wild rage and sinking into sick, black depression. He’d been responsible for the pilot gyros and their safe arrival. What had happened wasn’t his fault, but it was not his job merely to remain blameless. It was his job to get the gyros delivered and set up in the Space Platform. He had failed.

The black car braked to a stop. There was Major Holt. Joe had seen him six months before. He’d aged a good deal. He looked grimly at the two pilots.

“What happened?” he demanded. “You dumped your fuel! What burned like this?”

Joe said thickly: “Everything was dumped but the pilot gyros. They didn’t burn! They were packed at the plant!”

The co-pilot suddenly made an incoherent sound of rage. “I’ve got it!” he said hoarsely. “I know——”

“What?” snapped Major Holt.

“They—planted that grenade at the—major overhaul!” panted the co-pilot, too enraged even to swear. “They—fixed it so—any trouble would mean a wreck! And I—pulled the fire-extinguisher releases just as we hit! For all compartments! To flood everything with CO₂! But it wasn’t CO₂! That’s what burned!”

Major Holt stared sharply at him. He held up his hand. Somebody materialized beside him. He said harshly: “Get the extinguisher bottles sealed and take them to the laboratory.”

“Yes, sir!”

A man went running toward the wreck. Major Holt said coldly: “That’s a new one. We should have thought of it. You men get yourselves attended to and report to Security at the Shed.”

The pilot and co-pilot turned away. Joe turned to go with them. Then he heard Sally’s voice, a little bit wobbly: “Joe! Come with us, please!”

Joe hadn’t seen her, but she was in the car. She was pale. Her eyes were wide and frightened.

Joe said stiffly: “I’ll be all right. I want to look at those crates——”

Major Holt said curtly: “They’re already under guard. There’ll have to be photographs made before anything can be touched. And I want a report from you, anyhow. Come along!”

Joe looked. The motorcycles were abandoned, and there were already armed guards around the still-steaming wreck, grimly watching the men of the fog wagon as they hunted for remaining sparks or flame. It was noticeable that now nobody moved toward the wreck. There were figures walking back toward the edge of the field. What civilians were about, even to the mechanics on duty, had started out to look at the debris at close range. But the guards were on the job. Nobody could approach. The onlookers went back to their proper places.

“Please, Joe!” said Sally shakily.

Joe got drearily into the car. The instant he seated himself, it was in motion again. It went plunging back across the field and out the entrance. Its horn blared and it went streaking toward the town and abruptly turned to the left. In seconds it was on a broad white highway that left the town behind and led toward the emptiness of the desert.

But not quite emptiness. Far, far away there was a great half-globe rising against the horizon. The car hummed toward it, tires singing. And Joe looked at it and felt ashamed, because this was the home of the Space Platform, and he hadn’t brought to it the part for which he alone was responsible.

Sally moistened her lips. She brought out a small box. She opened it. There were bandages and bottles.

“I’ve a first-aid kit, Joe,” she said shakily. “You’re burned. Let me fix the worst ones, anyhow!”

Joe looked at himself. One coat sleeve was burned to charcoal. His hair was singed on one side. A trouser leg was burned off around the ankle. When he noticed, his burns hurt.

Major Holt watched her spread a salve on scorched skin. He showed no emotion whatever.

“Tell me what happened,” he commanded. “All of it!”

Somehow, there seemed very little to tell, but Joe told it baldly as the car sped on. The great half-ball of metal loomed larger and larger but did not appear to grow nearer as Sally practiced first aid. They came to a convoy of trucks, and the horn blared, and they turned out and passed it. Once they met a convoy of empty vehicles on the way back to Bootstrap. They passed a bus. They went on.

Joe finished drearily: “The pilots did everything anybody could. Even checked off the packages as they were dumped. We reported the one that blew up.”

Major Holt said uncompromisingly: “Those were orders. In a sense we’ve gained something even by this disaster. The pilots are probably right about the plane’s having been booby-trapped after its last overhaul, and the traps armed later. I’ll have an inspection made immediately, and we’ll see if we can find how it was done.

“There’s the man you think armed the trap on this plane. An order for his arrest is on the way now. I told my secretary. And—hm.... That CO₂——”

“I didn’t understand that,” said Joe drearily.

“Planes have CO₂ bottles to put fires out,” said the Major impatiently. “A fire in flight lights a red warning light on the instrument panel, telling where it is. The pilot pulls a handle, and CO₂ floods the compartment, putting it out. And this ship was coming in for a crash landing so the pilot—according to orders—flooded all compartments with CO₂. Only it wasn’t.”

Sally said in horror: “Oh, no!”

“The CO₂ bottles were filled with an inflammable or an explosive gas,” said her father, unbending. “Instead of making a fire impossible, they made it certain. We’ll have to watch out for that trick now, too.”

Joe was too disheartened for any emotion except a bitter depression and a much more bitter hatred of those who were ready to commit any crime—and had committed most—in the attempt to destroy the Platform.

The Shed that housed it rose and rose against the skyline. It became huge. It became monstrous. It became unbelievable. But Joe could have wept when the car pulled up at an angular, three-story building built out from the Shed’s base. From the air, this substantial building had looked like a mere chip. The car stopped. They got out. A sentry saluted as Major Holt led the way inside. Joe and Sally followed.

The Major said curtly to a uniformed man at a desk: “Get some clothes for this man. Get him a long-distance telephone connection to the Kenmore Precision Tool Company. Let him talk. Then bring him to me again.”

He disappeared. Sally tried to smile at Joe. She was still quite pale.

“That’s Dad, Joe. He means well, but he’s not cordial. I was in his office when the report of sabotage to your plane came through. We started for Bootstrap. We were on the way when we saw the first explosion. I—thought it was your ship.” She winced a little at the memory. “I knew you were on board. It was—not nice, Joe.”

She’d been badly scared. Joe wanted to thump her encouragingly on the back, but he suddenly realized that that would no longer be appropriate. So he said gruffly: “I’m all right.”

He followed the uniformed man. He began to get out of his scorched and tattered garments. The sergeant brought him more clothes, and he put them on. He was just changing his personal possessions to the new pockets when the sergeant came back again.

“Kenmore plant on the line, sir.”

Joe went to the phone. On the way he discovered that the banging around he’d had when the plane landed had made a number of places on his body hurt.

He talked to his father.

Afterward, he realized that it was a queer conversation. He felt guilty because something had happened to a job that had taken eight months to do and that he alone was escorting to its destination. He told his father about that. But his father didn’t seem concerned. Not nearly so much concerned as he should have been. He asked urgent questions about Joe himself. If he was hurt. How much? Where? Joe was astonished that his father seemed to think such matters more important than the pilot gyros. But he answered the questions and explained the exact situation and also a certain desperate hope he was trying to cherish that the gyros might still be repairable. His father gave him advice.

Sally was waiting again when he came out. She took him into her father’s office, and introduced him to her father’s secretary. Compared to Sally she was an extraordinarily plain woman. She wore a sorrowful expression. But she looked very efficient.

Joe explained carefully that his father said for him to hunt up Chief Bender—working on the job out here—because he was one of the few men who’d left the Kenmore plant to work elsewhere, and he was good. He and the Chief, between them, would estimate the damage and the possibility of repair.

Major Holt listened. He was military and official and harassed and curt and tired. Joe’d known Sally and therefore her father all his life, but the Major wasn’t an easy man to be relaxed with. He spoke into thin air, and immediately his sad-seeming secretary wrote out a pass for Joe. Then Major Holt gave crisp orders on a telephone and asked questions, and Sally said: “I know. I’ll take him there. I know my way around.”

Her father’s expression did not change. He simply included Sally in his orders on the phone.

He hung up and said briefly: “The plane will be surveyed and taken apart as soon as possible. By the time you find your man you can probably examine the crates. I’ll have you cleared for it.”

His secretary reached in a drawer for order forms to fill out and hand him to sign. Sally tugged at Joe’s arm. They left.

Outside, she said: “There’s no use arguing with my father, Joe. He has a terrible job, and it’s on his mind all the time. He hates being a Security officer, too. It’s a thankless job—and no Security officer ever gets to be more than a major. His ability never shows. What he does is never noticed unless it fails. So he’s frustrated. He’s got poor Miss Ross—his secretary, you know—so she just listens to what he says must be done and she writes it out. Sometimes he goes days without speaking to her directly. But really it’s pretty bad! It’s like a war with no enemy to fight except spies! And the things they do! They’ve been known even to booby-trap a truck after an accident, so anybody who tries to help will be blown up! So everything has to be done in a certain way or everything will be ruined!”

She led him to an office with a door that opened directly into the Shed. In spite of his bitterness, Joe was morosely impatient to see inside. But Sally had to identify him formally as the Joe Kenmore who was the subject of her father’s order, and his fingerprints had to be taken, and somebody had him stand for a moment before an X-ray screen. Then she led him through the door, and he was in the Shed where the Space Platform was under construction.

It was a vast cavern of metal sheathing and spidery girders, filled with sound and detail. It took him seconds to begin to absorb what he saw and heard. The Shed was five hundred feet high in the middle, and it was all clear space without a single column or interruption. There were arc lamps burning about its edges, and high up somewhere there were strips of glass which let in a pale light. All of it resounded with many noises and clanging echoes of them.

There were rivet guns at work, and there were the grumblings of motor trucks moving about, and the oddly harsh roar of welding torches. But the torch flames looked only like marsh fires, blue-white and eerie against the mass of the thing that was being built.

It was not too clear to the eye, this incomplete Space Platform. There seemed to be a sort of mist, a glamour about it, which was partly a veiling mass of scaffolding. But Joe gazed at it with an emotion that blotted out even his aching disappointment and feeling of shame.

It was gigantic. It had the dimensions of an ocean liner. It was strangely shaped. Partly obscured by the fragile-seeming framework about it, there was bright plating in swelling curves, and the plating reached up irregularly and followed a peculiar pattern, and above the plating there were girders—themselves shining brightly in the light of many arc lamps—and they rose up and up toward the roof of the Shed itself. The Platform was ungainly and it was huge, and it rested under a hollow metal half-globe that could have doubled for a sky. It was more than three hundred feet high, itself, and there were men working on the bare bright beams of its uppermost parts—and the men were specks. The far side of the Shed’s floor had other men on it, and they were merely jerkily moving motes. You couldn’t see their legs as they walked. The Shed and the Platform were monstrous!

Joe felt Sally’s eyes upon him. Somehow, they looked proud. He took a deep breath.

She said: “Come on.”

They walked across acres of floor neatly paved with shining wooden blocks. They moved toward the thing that was to take mankind’s first step toward the stars. As they walked centerward, a big sixteen-wheel truck-and-trailer outfit backed out of an opening under the lacy haze of scaffolds. It turned clumsily, and carefully circled the scaffolding, and moved toward a sidewall of the Shed. A section of the wall—it seemed as small as a rabbit hole—lifted inward like a flap, and the sixteen-wheeler trundled out into the blazing sunlight. Four other trucks scurried out after it. Other trucks came in. The sidewall section closed.

There was the smell of engine fumes and hot metal and of ozone from electric sparks. There was that indescribable smell a man can get homesick for, of metal being worked by men. Joe walked like someone in a dream, with Sally satisfiedly silent beside him, until the scaffolds—which had looked like veiling—became latticework and he saw openings.

They walked into one such tunnel. The bulk of the Platform above them loomed overhead with a crushing menace. There were trucks rumbling all around underneath, here in this maze of scaffold columns. Some carried ready-loaded cages waiting to be snatched up by hoists. Crane grips came down, and snapped fast on the cages, and lifted them up and up and out of sight. There was a Diesel running somewhere, and a man stood and stared skyward and made motions with his hands, and the Diesel adjusted its running to his signals. Then some empty cages came down and landed in a waiting truck body with loud clanking noises. Somebody cast off the hooks, and the truck grumbled and drove away.

Sally spoke to a preoccupied man in shirt sleeves with a badge on an arm band near his shoulder. He looked carefully at the passes she carried, using a flashlight to make sure. Then he led them to a shaft up which a hoist ran. It was very noisy here. A rivet gun banged away overhead, and the plates of the Platform rang with the sound, and the echoes screeched, and to Joe the bedlam was infinitely good to hear. The man with the arm band shouted into a telephone transmitter, and a hoist cage came down. Joe and Sally stepped on it. Joe took a firm grip on her shoulder, and the hoist shot upward.

The hugeness of the Shed and the Platform grew even more apparent as the hoist accelerated toward the roof. The flooring seemed to expand. Spidery scaffold beams dropped past them. There were things being built over by the sidewall. Joe saw a crawling in-plant tow truck moving past those enigmatic objects. It was a tiny truck, no more than four feet high and with twelve-inch wheels. It dragged behind it flat plates of metal with upturned forward edges. They slid over the floor like sledges. Cryptic loads were carried on those plates, and the tow truck stopped by a mass of steel piping being put together, and began to unload the plates.

Then the hoist slowed abruptly and Sally winced a little. The hoist stopped.

Here—two hundred feet up—a welding crew worked on the skin of the Platform itself. The plating curved in and there was a wide flat space parallel to the ground. There was also a great gaping hole beyond. Though girders rose roofward even yet, this was as high as the plating had gone. That opening—Joe guessed—would ultimately be the door of an air lock, and this flat surface was designed for a tender rocket to anchor to by magnets. When a rocket came up from Earth with supplies or reliefs for the Platform’s crew, or with fuel to be stored for an exploring ship’s later use, it would anchor here and then inch toward that doorway....

There were half a dozen men in the welding crew. They should have been working. But two men battered savagely at each other, their tools thrown down. One was tall and lean, with a wrinkled face and an expression of intolerable fury. The other was squat and dark with a look of desperation. A third man was in the act of putting down his welding torch—he’d carefully turned it off first—to try to interfere. Another man gaped. Still another was climbing up by a ladder from the scaffold level below.

Joe put Sally’s hand on the hoist upright, instinctively freeing himself for action.

The lanky man lashed out a terrific roundhouse blow. It landed, but the stocky man bored in. Joe had an instant’s clear sight of his face. It was not the face of a man enraged. It had the look of a man both desperate and despairing.

Then the lanky man’s foot slipped. He lost balance, and the stocky man’s fist landed. The thin man reeled backward. Sally cried out, choking. The lanky man teetered on the edge of the flat place. Behind him, the plating curved down. Below him there were two hundred feet of fall through the steel-pipe maze of scaffolds. If he took one step back he was gone inexorably down a slope on which he could never stop.

He took that step. The stocky man’s face abruptly froze in horror. The lanky man stiffened convulsively. He couldn’t stop. He knew it. He’d go back and on over the rounded edge, and fall. He might touch the scaffolding. It would not stop him. It would merely set his body spinning crazily as it dropped and crashed again and again before it landed two hundred feet below.

It was horror in slow motion, watching the lean man stagger backward to his death.

Then Joe leaped.

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