They did not pause, even to catch their breath, for the first twenty minutes as Tom led them swiftly and silently down through the maze of corridors and chutes that made up the ventilation system of the huge ship. Greg lost his bearing completely in the first twenty seconds; each time his brother paused at a junction of tubes, he felt a wave of panic rise up in his throat ... suppose they lost themselves in here! He heard Johnny's trousers flapping behind him, saw Tom's figure flit past another grill up ahead, and plunged doggedly on.

It was amazingly hard to move quietly. Even in stocking feet they made a soft thud with each footfall.

But there was no sign of detection, no sound of alarm. Finally they came out into a large shaft which allowed them to stand upright, and they stopped to catch their breath.

"Main tube to the living quarters," Tom said when they had caught up to him. "Joins with the lower-level tube by a series of chutes. We've actually been circumnavigating the ship ... I wanted to get as far away from that lounge compartment as possible, in case they check up on you right away."

"We can't have much time," Johnny said. "That second guard must have been coming to relieve the other, and when the first one doesn't report back, they'll smell something fishy."

They talked it over for a moment. Johnny had been careful to leave the hatchway into the corridor ajar before he climbed into the ventilator shaft, and then he had pulled the shaft snugly into place behind him. Anyone who came would find two unconscious guards, a burnt-out hole in the wall, and the door unlocked.

"We'll hope that he takes things at face value, and assumes we're at large in the ship somewhere, for a while at least," Johnny said. "That hole in the wall is going to set them back a couple of steps, too."

"But they'll sound the alarm, at least," Tom said.

"You bet they will! They'll have every man on the crew shaking down the ship for us. But they may not think of the ventilators until they can't find us anywhere else."

"But sooner or later they're bound to think of it."

"That's true," Johnny said. "Unless they keep seeing us in the ship. The way I figure it, this crew has been on battle stations plenty of times. They'll be able to search the whole ship in half an hour. We're just going to have to show ourselves ... at least enough to keep them searching."

"Well, what if they do think of the ventilators?" Greg said. "They'd still have a time finding us."

"Maybe, but don't underestimate Tawney. He might just mask up his crew and flood the tubes with cyanide."

They thought about that for a minute. There was no sound here but their own breathing, and the low chug-chug-chug of the pumps somewhere deep in the ship. Momentarily they expected to hear the raucous clang of the alarm bell, as some crew member or another walked into the lounge and found them gone. But so far there was no sign they had been discovered missing. "No," Johnny said finally, "if we just hide out in here, and hope for a chance at one of the scout ships, they'll find us eventually. But we've got three big advantages, if we can figure out how to use them. That fancy gun, for one. A way to get around the ship, for another ... and the fact that there's one more of us than they count on." He flipped on his pocket flash, began drawing lines on the dusty floor of the shaft. "My idea is to keep them so busy fighting little fires that they won't have a chance to worry about where the big one is."

He drew a rough outline-sketch of the organization of the ship. "This look right to you, from what you've seen?" he asked Tom.

"Pretty much," Tom said. "There are more connecting tubes."

"All the better. We want to get the generators with our little toy here first. That'll darken the ship, and put the blowers out of commission in case they think of using gas. Also, it will cut out their computers and missile-launching rigs, which might give us a chance to get a scout-ship away in one piece if we could get aboard one."

"All right, the generators are first," Tom said. "But then what? There are four hundred men on this ship. They'll have every airlock triple guarded. They'll block us for sure."

"Not when we get through, they won't," Johnny grinned. "We've got an old friend aboard who's going to help us."

"Friend?"

"Ever hear of panic?" Johnny said. "Just listen a minute."

Quickly then, he outlined his plan. Tom and Greg listened, watched Johnny make marks with his finger in the dust. When he finished, Greg whistled softly. "You missed your life work," he said. "You should have gone into crime."

"If I'd had a ghost to help me, I might have," Johnny said.

"It's perfect," Tom said, "if it works. But it all depends on one thing ... keeping it rolling after we start...."

For another five minutes they went over the details. Then Johnny clapped them each on the shoulder. "It's up to you two," he said. "Let's go."

They moved down the large shaft to the place where it broke into several spurs. Johnny started down the chute toward the engine rooms; Tom and Greg headed in opposite directions toward the main body of the ship. Just as they broke up, they heard a muffled metallic sound from the nearest compartment grill.

It was the clang-clang-clang of the orbit-ship's general alarm.

Crewmen stopped with food halfway to their mouths, jerked away from tables. Orders buzzed along a dozen wires, and section chiefs began reporting their battle-stations alert and ready. Finally Tawney snapped on the general public address system speaker. "Now get this," he roared. "I want every inch of this ship searched ... every corridor, every compartment. I want a special crew standing by for missile launching. I want double guards at every airlock. If they get a ship away from here, the man who lets them through had better be dead when I find him...." He broke off, clutching the speaker until his voice was under control again. "All right, move. They're armed, but there's no place they can go. Find them."

A section-chief came back over the speaker. "Dead or alive, boss?"

"Alive, you idiot! At least the Hunter brat. I'll take the other one any way you can get him."

He switched off, and waited, pacing the control cabin like a caged animal. Ten minutes later a buzzer sounded. "Hydroponics, boss. All clear."

"No sign of them?"

"Nothing."

Another buzz. "Number seven ore hold. Nothing here."

Still another buzz. "Crew's quarters. Nothing, boss."

One by one the reports came in. Fuming, Tawney checked off the sections, watched the net draw tighter throughout the ship. They were somewhere, they had to be....

But nobody seemed to find them.

He was buzzing for his first mate when the power went off. The lights went out, the speaker went dead in his hand. The computers sighed contentedly and stopped computing. Abruptly the emergency circuits went into operation, flooding the darkness with harsh white lights. The intercom started buzzing again.

"Engine room, boss."

"What happened down there?" Tawney roared.

The man sounded like he'd just run the mile. "Generators," he panted. "Blown out."

"Well, get somebody in there to fix them. Have a crew seal off the area...."

"Can't, boss. Fix them, I mean."

"Why not? What have we got electricians for?"

"There's nothing left to fix. The generators aren't wrecked ... they're demolished...."

"Then get the pair that did it...."

"They're not here. We've been sealed up tight. There's no way anybody could have gotten in here...."

After that, things began to get confusing.

For a while Merrill Tawney thought that his crew was going crazy ... and then he began to wonder if he were the one who was losing his mind.

Whatever the case, Merrill Tawney was certain of one thing. The things that were happening on his orbit-ship could not possibly be happening.

A guard in one of the outer shell storage holds called in with a disquieting report. Greg Hunter, it seemed, had just been spotted vanishing into one of the storage compartments from the main outer-shell corridor. When the guard had broken through the jammed hatchway to collar his trapped victim, there was no sign of the victim anywhere around.

At the same moment, a report came in from a guard on the opposite side of the ship. He had just spotted Greg Hunter there, it seemed, moving down a spur corridor. The guard had held his fire (according to Tawney's orders) and summoned help to corner the quarry ... but when help arrived, the quarry had vanished.

Five minutes later the Hunter boy was discovered in the Hydroponics section, busily reducing all the yeast vats to shambles with a curious weapon that seemed to eat holes in things. It ate the deck out from under the guard's feet, sending him plunging through the floor into the galley. By the time he had scrambled back again, the Hunter boy was gone, and a rapid move to seal off the region failed to turn him up again. The guard was upset; Tawney was a great deal more upset, because at the time Greg Hunter was (reportedly) playing havoc with the yeast-vats in Hydroponics he was also (reportedly) knocking guards down like ten-pins in the main corridor off the engine room while reinforcements tried to pin him down with a wide-beam stunner....

Quite suddenly emergency circuits closed and lights flashed in the control cabin, the special signal for a meteor-collision with the outer shell in No. 3 hold. Tawney signalled for the section chief frantically. "What's happening down there?"

"I can't talk," the section chief gasped. "Gotta get into a suit, we're leaking in here...."

"Well, plug up the hole!"

"The hole's four feet wide, sir!" There was a fit of coughing and the contact broke. The signals for No. 4 hold and No. 5 hold were flashing now; while the crew members in the vicinity scrambled for pressure suits someone systematically proceeded to blow holes in No. 9, No. 10 and No. 11 holds....

It was impossible. The reports came in thick and fast. Greg Hunter was in two places at once, and everywhere he went ... in both places ... there was a trail of unbelievable destruction. Bulkheads demolished, gaping holes torn in the outer shell, the air-reconditioning units smashed beyond repair.... Tawney buzzed for his first mate.

An emergency switch cut into the line, with the frantic voice of a section chief. Johnny Coombs had been spotted disappearing into the ventilator shaft in the engine sector. "Well, go in after him!" Tawney screamed. He got his first mate finally, and snarled orders into the speaker. "They're in the ventilators. Get a crew in there and stop them."

But it was dark in the ventilator shafts. No emergency lights in there. Worse, the crewmen were hearing the things that were being whispered around the ship. The ventilator shafts yawned menacingly before them; they went in reluctantly. Once in the dark maze of tunnels, identification was difficult. Two guards met each other headlong in the darkness, and put each other out of the fight in a flurry of nervous stunner-fire. While they searched more of the holds were broken open, leaking air through gaping rents in the hull....

Tawney felt the panic spreading; he tried to curb it, and it spread in spite of him. The fugitives were appearing and disappearing like wraiths. Reports back to control cabin took on a frantic note, confused and garbled. Now the second-level bulkheads were being attacked. Over a third of the compartments were leaking precious air into outer space.

When a terrified section chief came through with a report that two Greg Hunters had been spotted by the same man at the same time, and that the guards in the sector were shooting at anything that moved, including other guards, Tawney made his way to the radio cabin and put through a frantic signal to Jupiter Equilateral headquarters on Mars.

The contact took forever, even with the ship's powerful emergency boosters. By the time someone at headquarters was reading him, Tawney's report sounded confused. He was trying for the third time to explain, clearly and logically, how two men and a ghost were scuttling his orbit-ship under his very feet when one wall of the cabin vanished in a crackle of blue fire, and he found himself staring at two Greg Hunters and a grim-faced Johnny Coombs.

He made squeaky noises into the microphone and dropped it with a crash. He groped for a chair; Johnny jerked him to his feet again. "A scout-ship," he said tersely. "Clear it for launching. We want one with plenty of fuel, and we don't want a single guard anywhere near the airlock." He picked up an intercom microphone and thrust it into the little fat man's trembling hand. "Now move! And you'd better be sure they understand you, because you're coming with us."

Merrill Tawney stared first at Tom, then at Greg, and finally at the microphone. Then he moved. The orders he gave to his section chiefs were very clear and concise.

He had never argued with a ghost before, and he didn't care to start now.

It was over so quickly that it seemed to Tom it had just begun, and if so much had not been at stake, it might have been fun.

It had been the gun ... the remarkable gun that Roger Hunter had left as his legacy ... that had been the key. It ate through steel and aluminum alloy like putty. Whatever its power source, however it worked, by whatever means it had been built, there had been no match for it on the orbit-ship.

It had worked ... and that was all that mattered right then.

With it, and with the advantage of a ghost that walked like a man ... Tom Hunter, to be exact ... they had reduced the Jupiter Equilateral orbit-ship to a smoking wreck in something less than thirty minutes.

The signal came back that a scout-ship was ready, unguarded. Johnny prodded Tawney with the stunner. "You first," he said.

"But where are you taking me?"

"You'll see," Johnny said.

"It was a trick," Tawney said, glaring at Tom. "They told me they shot your ship to pieces...."

"The ship, yes," Tom said. "Not me."

"Well ... well, that's good, that's good," Tawney said quickly. He turned to Greg. "You don't have to take me back ... the bargain is still good...."

"Move," Johnny Coombs said.

With Tawney between them, Greg and Tom marched down the corridor toward the airlock, with Johnny bringing up the rear. No one stopped them. No one even came near them. One crewman stumbled on them in the corridor; he saw Tawney with a gun in his back, and fled in terror.

They found the scout-ship, and strapped Tawney down to an accelleration bunk, binding his hands and feet so he couldn't move. Greg checked the controls while Tom and Johnny strapped down. A moment later the engines fired, and the leaking wreck of the orbit-ship fell away, dwindling and disappearing in the blackness of space.

It was a quiet journey. The red dot that was Mars grew larger every hour. One of the three stayed awake at all times to watch Tawney while the others slept. During the second rest period, Tom woke up while Greg was on duty.

"How's our prisoner doing?" Tom asked.

"No problem there, he can barely move. I almost wish he'd try something, he's too quiet."

It was true. Tawney had recovered from his shock ... but rather than grow more worried as Mars grew large on the screen, he seemed to become more cheerful by the minute. "He doesn't seem very worried, does he?" Tom said.

"No, and it doesn't quite add. We've got enough on him to get Jupiter Equilateral pushed right out of the Belt."

"I'd still feel better if we had the whole picture for the Major," Tom said. "We still don't know what Dad found, or where he hid it...."

The uneasiness grew. Tawney ignored them, staring at the image of the red planet on the viewscreen almost eagerly. Then, eight hours out of Sun Lake City a U.N. Patrol ship appeared, moving toward them swiftly. "Intercepting orbit," Greg said. "Looks like they were waiting for us."

They watched as the big ship moved in to tangential orbit, matching its speed to theirs. Then Greg snapped the communicator switch. "Sound off," he said cheerfully. "We've got a prize for you."

"Stand by, we're boarding you," the Patrol sent back. "And put your weapons aside."

Four scooters broke from the side of the Patrol ship. Greg activated the airlock. Five minutes later a man in Patrol uniform with captain's bars stepped into the control cabin, a stunner on ready in his hand. Three Patrolmen came in behind him.

The captain looked around the cabin, then saw Tawney, and took a deep breath. "Well, thank the stars you're safe at any rate. Pete, Jimmy, take the controls."

"Hold on," Greg said. "We don't need a pilot."

The Captain looked at him. "Sorry, but we're taking you in. There won't be any trouble unless you make it. You three are under arrest, and I'm authorized to make it stick if I have to. I suggest you just cooperate."

They stared at him. Then Johnny said, "What are the charges?"

"You ought to know," the Captain said. "We have a formal complaint from the main offices of Jupiter Equilateral, charging you with piracy, murder, kidnapping of a company official, and totally wrecking a company orbit ship. I don't quite see how you managed it, but we're going to find out in short order."

There was a stunned silence in the cabin, and then a sound came from the rear of the cabin.

Merrill Tawney was laughing.