Roger Manning opened his eyes, then closed them. He lay perfectly still and listened. The sound he heard was the unmistakable blasting roar of a spaceship. But there was another sound, much closer. In fact, it was in the room with him.

He opened one eye to see Quent Miles moving about in the one-room, airtight space hut which had been his jail for the last week. Miles was throwing clothes into a space bag, keeping a wary eye on Roger, sprawled on the bunk. Hoisting the bag to his shoulder, Miles closed the face plate of his space helmet, turned to the air lock, and stepped inside, slamming the portal behind him. From the bunk, Roger could hear the hissing of the change of pressure inside the lock from normal to the vacuum of space outside.

The entire week had been a time of waiting and wondering. He couldn't understand Miles' actions in taking him prisoner the moment before blast-off from Earth, and then keeping him at the asteroid, seemingly giving up all chances of winning the race.

Roger waited until he was sure that the black-clad spaceman had gone, then he sat up and worked desperately on the thin metal chain binding his wrists. He had been working on one of the links ever since his arrival at Miles' strange asteroid base, scraping it against the rough metal edge of one of the legs of his bunk. Two days before, he had succeeded in wearing it down to a point where he could snap it easily when the opportunity came for him to make a break. But so far the chance had not presented itself. He had been kept prisoner in the space hut, and Miles had pushed his food in through a vent in the air lock. Now, however, with the sound of the spaceship outside, the cadet decided it was time for action.

Working quickly, Roger snapped the link and tore off the chain, freeing his hands. He allowed himself the longed-for luxury of stretching just once, and then crossed to the small locker beside the air-lock door to take out a space suit. He climbed into it hurriedly, secured the helmet, and began searching the small room for a weapon. In the bottom of a chest he found a rocketman's wrench. Grasping it tightly, he stepped into the air lock. Just before he turned on the oxygen in his space suit, he listened again for the noise of the blasting ship. Then he grinned as he realized that it wasn't the noise of the ship he heard, but the vibration it created on the surface of the asteroid. Sound wouldn't travel through the vacuum of space outside. Suddenly it stopped and Roger realized the tubes were being blasted in preparation for take-off. The young cadet closed the inner portal of the lock, adjusted the pressure, turned on the oxygen of his suit, and waited. In a moment the indicator showed the pressure to be equal to that outside in space, and he opened the outer portal cautiously.

A section of the asteroid belt swam above him. Hundreds of small planetoids and various-sized pieces of space junk drifted in the cold vacuum of space overhead. Roger looked around. The asteroid he was on was so small and the horizon such a short distance away that the base of Miles' giant black ship was half-covered by the curvature of the planetoid.

Holding the wrench tightly in his hand, the blond-haired cadet circled around the space hut cautiously, looking for Quent Miles, but the spaceman was nowhere in sight. He had walked all the way around the hut and back to the air lock when he saw a movement out of the corner of his eye. It was Miles, returning to the space hut. Moving quickly, Roger ducked behind a huge boulder and waited for Miles to come closer. It would be impossible to hit Miles with the heavy wrench. The space helmet would ward off the blow. His only chance was to get aboard the ship while Miles was inside the hut. And he would have to move fast. When Miles discovered the hut was empty, he would come looking for the young cadet.

But to the cadet's great relief, Miles went past the hut and disappeared over the horizon of the asteroid in the opposite direction.

Slipping out from behind the boulder and utilizing the near lack of gravity, Roger ran in giant leaps toward the black spaceship. His last jump brought him to the base of the ship where he quickly clambered up the ladder, opened the portal, and slipped into the air lock. In a matter of seconds he had built up the pressure in the lock to equal the pressure inside the ship. He opened the inner portal and raced up the ladder to the control deck. Throwing himself into the pilot's chair, he prepared to raise ship. Then he slumped in despair. The master switch had been removed. It was impossible for him to blast off!

He leaped out of the chair and scrambled up the ladder to the radar deck. He flipped on the audioceiver and nervously waited for the tubes to warm up. Nothing happened. Only then he remembered that the communications would not work without power from the generators and they could not be started without the master switch.

"Boy! He sure wasn't taking any chances of me getting away and leaving him here," Roger muttered to himself, as he turned back to the ladder and climbed down to the air lock. He stepped inside, and crossing to the small viewport, looked out over the dead landscape of the tiny world for a sign of Quent Miles. He saw the black-clad spaceman returning toward the hut. Roger held his breath. If Miles went into the hut this time and found him missing, he would know that the cadet was aboard the ship. "Manning," Roger said to himself, "if you ever needed luck, you need it now!"

Miles walked slowly, as if in no hurry, still heading for the space hut. But as Roger held his breath in fear, he passed it again, without so much as pausing to look at it.

Roger grinned. "Spaceman, you are going to say your prayers every night after this," he murmured.

The cadet turned, and racing as fast as the cumbersome space suit would allow him, headed toward the power deck. Passing the galley, he snatched up several plastic packages of food.

Down on the power deck, Roger went directly to the lead baffling shields around the reactant chambers and carefully squeezed between them and the outer hull. It was going to be a rough ride on the power deck, jammed in behind the firing chambers, but at least he was hidden—and more important, free.

He listened for the clank of metal shoes on the ladder above him. When he heard them, followed closely by the slam of the air-lock portal, he grinned in satisfaction. Opening one of the plastic bags, he began to eat.

In a moment the ship came to life and the power deck became a raging torrent of noise and vibration. As Roger braced himself, he felt the ship quiver and then shake, as under heavy acceleration, it blasted off into space.

Captain Strong and young Sergeant Morgan hailed a passing jet truck loaded with Space Marines. "Get me to Commander Walters right away, Lieutenant!" said Strong to the young officer in charge. "This is an emergency."

"Yes, sir," acknowledged the young officer, and sent the truck roaring down the empty avenue toward the electronics building where Walters was still checking the reports on the screens.

"Is there anything new, sir?" asked the young officer. "Have the technicians been able to find out what's making the screens fail?"

"We're on the right track, Lieutenant," said Strong shortly. "Can't you get any more speed out of this thing?"

It would be a rough ride, but at least he was hidden

"Yes, sir," replied the officer. He rammed the accelerator to the floor and the small truck blasted through the streets as though shot out of cannon.

In a few minutes the truck screamed to a halt in front of the building and Strong leaped toward the door, followed closely by Sergeant Morgan and the Space Marine lieutenant.

Strong found Walters before the telemetering board waiting impatiently for some figures Dr. Joan Dale had sent him to be analyzed and evaluated. He spun around when Strong entered the room at a dead run.

"Steve!" he exclaimed. "What's the matter? Anything happen to the cadets?"

"We didn't find them, sir, but we did find something else. We—" Before Strong could finish, the calculator began pouring out its answers.

"Excuse me, Steve! These figures could tell us why the screens are failing."

"But I know why they're failing, sir!" shouted Strong.

"You know what?" exclaimed Walters.

As all the men in the room stared at him, Strong hurriedly told the commanding officer what he had found, concluding, "I think the room I stumbled into was used as a repair shop. But it was gas-free and pure oxygen was coming out of the pipe I described."

"I see," said Walters grimly. "Let me check that against these figures." He turned to the calculator and with the assistance of Joe Howard, Kit Barnard, and the chief electronics engineer began studying the figures.

Strong paced up and down nervously. The faces of the technicians in the room clearly showed the strain they had been under the past few days. And when they heard the startling news Strong had delivered, there wasn't one who didn't feel his fingers tighten into fists at Brett and Miles' selfishness.

Walters straightened up and glanced at the faces of the men around him. "Well, gentlemen," he said. "I think the figures speak for themselves."

There was a murmur of agreement. Walters turned back to Strong. "Those figures prove conclusively that what you say is true. It is impossible for the screens to collapse except from a vital leak—exactly such a leak as you have described."

Walters turned and began to snap orders to the men around him. "I want every available man sent out on the double. I want every inch of that area searched for an opening to a mine shaft or anything that leads underground. Take half the men off the spaceport detail."

"Shall we continue evacuation operations for the miners and their families?" asked the young Space Marine lieutenant. "There is quite a force of men out there that could be used in the search."

"What do you think, Steve? Should we take off the guardsmen and suspend evacuation in the hope that we can find that leak?"

"I would say yes, Commander," said Strong. "Your figures and those Dr. Dale sent you point to a leak of this nature."

"Very well, Lieutenant," said Walters. "Order every man to the area and begin search operations immediately. I want that leak found—and found fast! And I want Charles Brett and Quent Miles arrested at once!"

Tom and Astro bent over the lead boxes again and heaved them to their shoulders. A quick glance showed them that Miles had not followed them to the floor of the cavern as he had done before, but had remained on guard on the balcony.

As they struggled to lift the boxes to their shoulders, Tom whispered out of the side of his mouth, "I know how we can get out of here, Astro."

"How?"

"Since Brett is staying on the ship for this trip, Miles is going to have trouble watching both of us."

"Yeah, I know," muttered Astro. "Want me to jump him?"

"No," Tom growled. "Miles has been trailing us through the tunnel by twenty to thirty feet each trip. When we pass that spot where the light is, you drop your box. He'll be watching you then and that will give me a chance to grab that booby trap you took apart, remember?"

"Yeah!"

"O.K. Now remember, when I give you the word, you drop your box on the right-hand side of the tunnel."

"Hurry up down there!" yelled Miles from the balcony. "We haven't got all night."

"Keep your shirt on, buster," growled Astro. "We're tired."

The two cadets balanced the heavy lead boxes on their shoulders, and, with Tom leading the way, climbed up the stairs past Miles and started up the tunnel in front of the black-suited spaceman.

They walked slowly, side by side, and as before, Miles stayed a good twenty paces behind them. As they neared the light where they knew the explosive charge would be, Tom began slowing his pace.

"Come on, get going, Corbett!" Miles yelled.

"He's tired," said Astro. "Leave him alone."

"What are you, his protector?" snarled Miles. "Get going, I said."

"O.K.," said Tom, struggling forward.

They came closer and closer to the light. Tom glanced at Astro and winked. Astro winked back and braced himself to fake the accident.

As closely as Tom could remember, Astro had tossed the charge to one side about ten feet beyond the light. If he knew exactly where it was, he could fall forward on top of it and stuff it in his tunic. He tried to recreate the scene as it happened. They passed under the light. One step ... two steps ... three steps.... "Now, Astro," Tom whispered.

The big cadet lunged to one side, dropping the heavy box to the floor. At the same time, Tom dropped his box and lunged forward, arms outstretched, feeling along the floor for the precious explosives.

Miles ran up quickly, ray gun cocked and ready.

"Get up!" he shouted. "Get up or I'll freeze you both and leave you here!"

Tom and Astro struggled to their feet. They lifted the heavy boxes to their shoulders and started down the tunnel again.

When Astro dared a glance at Tom, he saw his unit mate grin and wink at him. Astro winked back. Suddenly it seemed that the heavy lead box was as light as air!