Tom knew now that it was the right thing to do. There was no question, after the Major's story, of what Dad had been doing out in the Belt at the time he had been killed. He had been doing a job that was more important to him than asteroid mining ... but he had found something more important than his own life, and had no chance to send word of what he had found back to Major Briarton on Mars. That had been the unforeseeable part of the trap.

But now, of course, the Major had to know.

The Mars Coordinator looked at the thing on the desk for a long moment before he reached out to touch it. The bright metal gleamed in the light, pale gray, lustrous. The Major picked it up, balanced it expertly in his hand, and a puzzled frown clouded his face. He examined it minutely.

"What is this thing?" he said.

"Suppose you tell us," Johnny Coombs said from across the room.

"It looks like a gun."

"That's what it is, all right."

"You've fired it?"

"Yes ... but I wouldn't fire it in here, if I were you," Johnny said. "You were wondering how we wrecked Tawney's orbit-ship so thoroughly. That's your answer right there." He told about the hole in the bulkhead, the way the ship's generators had melted like clay under the powerful blast of the weapon.

The Major could hardly control his excitement. "Where did you get it?" he asked, turning to Tom.

"From the space pack that you turned over to us. I didn't even look at it, until we needed a gun in a hurry. I just assumed it was Dad's revolver."

"And your father found it somewhere in the Belt," the Major said softly. He looked at the weapon again, shaking his head. "There isn't any such gun," he said finally. "These things you say it could do ... they would require energy enough to break down the cohesive forces of molecules. There isn't any way we know of to harness that kind of energy and channel it in a hand weapon. Nobody on Earth...."

He broke off and stared at them.

"That's right," Johnny said. "Nobody on Earth."

"You mean ... extraterrestrial?"

"There isn't any other answer," Johnny said. "Look at the thing, Major. Feel it. Does it feel like it was made for a human hand? It doesn't fit, it doesn't balance, you have to hold it with both hands to aim it...."

"But where did it come from?" the Major said. "We've never had visitors from another star system ... not in the course of recorded history. And we know that Earthmen are the only intelligent creatures in our Solar System."

"You mean that they're the only ones now," Tom said.

"Or any other time."

"We don't know that, for sure," Tom said.

"Look, we've explored Venus, Mars, all the major satellites. If there had ever been intelligence on any of them, we'd have known it."

"Maybe there was a planet that Earthmen haven't explored," Tom said. "Even Dad tried to tell us that. The quotation from Kepler that he scribbled down in his log ... 'Between Jupiter and Mars I will put a planet.' Why would Dad have written that? Unless he had suddenly discovered proof that there had been a planet there?"

"You mean this ... this gun," the Major said.

"And whatever else he found."

"But there's never been any proof of that theory ... not even a hint of proof."

"Maybe Dad found proof. There are hundreds of thousands of asteroid fragments out there in the Belt, and only a few hundred of them have ever been examined by men."

On the desk the strange weapon stared up at them. Evidence, mute evidence, and yet its very existence said more than a thousand words. It was there. It could not be denied.

And someone ... or something ... had made it.

Slowly the Major pulled himself to his feet. "It must have happened after his last message to me," he said. "It wasn't part of the scheme we had set up, but he made a strike just the same ... an archeological strike ... and this gun was part of it." He picked up the weapon, turned it over in his hand. "But it was days after that last message before his signal went off, and the Patrol ship moved in."

"It makes sense," Johnny Coombs said. "He found the gun, and something more."

"Like what?"

"I wouldn't even guess," Johnny said. "A planet with a race of creatures intelligent enough and advanced enough to make a weapon like that ... it could have been anything. But whatever it was, it must have scared him. He must have known that a company ship might turn up any minute ... so he hid whatever he had found, and all he dared to leave was a hint."

"And now it's vanished," the Major said. "The big flaw in the whole idea. My Patrol ship found nothing when it searched the region. You looked, and drew a blank. The company men scoured the area." He spread his hands helplessly. "You see, it just won't hold up, not a bit of it. Even with this gun, it won't hold up. We've got to find the answer."

"It's out there somewhere," Tom said doggedly. "It's got to be."

"But where? Don't you see that everything hangs on that one thing? If we could prove that your father found something just before he was killed, we could tear Jupiter Equilateral's case against you into shreds. We could charge them with piracy and murder, and make it stick. We could break their power once and for all ... but until we know what Roger Hunter found, we're helpless. They'll take you three to court, and I won't be able to stop them. And if you lose that case, it may mean the end of U.N. authority on Mars."

"Then there's just one thing to do," Johnny Coombs said. "We've got to find Roger Hunter's bonanza."

It was almost midnight when they left the Major's office, a gloomy trio, walking silently up the ramp to the Main Concourse, heading toward the living quarters.

They had been talking with the Major for hours, going over every facet of the story, wracking their brains for the answer ... but the answer had not come.

Roger Hunter had found something, and hidden it so well that three groups of searchers had failed to discover it. After seeing the gun, the Major was convinced that there had indeed been a discovery made. But whatever that discovery had been, it was gone as if it had never existed ... as if by some sort of magic it had been turned invisible, or conjured away to another part of the Solar System.

Finally, they had given up, at least for the moment. "It has to be there," the Major had said wearily. "It hasn't vanished, or miraculously ceased to exist. We know he was working on one claim, one asteroid. There were no other asteroids in the region ... and even the ones within suicide radius have been searched."

"It's there, all right," Tom said. "We're missing something, that's all."

"But what? Asteroids have stable orbits. Nobody can just make one disappear...."

They had called it a night, finally.

Once home they found more bad news waiting. There were two messages on the recordomat. The first was an official summons to appear before the United Nations Board of Investigations at 9:00 the following morning to answer "certain charges placed against the above named persons by the Governing Board of Jupiter Equilateral Mining Industries, and by one Merrill Tawney, plaintiff, representing said Governing Board." They listened to the plastic record twice. Then Greg tossed it down the waste chute.

The other message was addressed to Greg, from the Commanding Officer of Project Star-Jump. The message was very polite and regretful; it was also very firm. The pressure of the work there, in his absence, made it necessary for the Project to suspend Greg on an indefinite leave of absence. Application for reinstatement could be made at a later date, but acceptance could not be guaranteed....

"Well, I might have expected it," Greg said, "after what the Major told us. The money for Star-Jump must have been coming from somewhere, and now we know where. The company probably figures to lay claim on any star-drive that's ever developed." He dropped the notice down the chute, and laughed. "I guess I really asked for it."

"You mean I pushed you into it," Tom said bitterly. "If I'd kept my big mouth shut at the very start of this thing, you'd have gone back to the Project and that would have been the end of it...."

Greg looked at him. "You big bum, do you think I really care?" He grinned. "Don't feel too guilty, Twin. We've been back to back on this one."

He pulled off his shirt and walked into the shower room. Johnny Coombs was already stretched out on the sofa, snoring softly.

Quite suddenly the room seemed hot and stuffy, oppressive. He couldn't make his thoughts come straight. There had been too much thinking, too much speculation. Tom stood up and slipped on his jacket.

He had to walk, to move about, to try to think. He slipped open the door, and started for the ramp leading to the Main Concourse.

There was an answer, somewhere.

He walked on along the steel walkways, trying to clear his mind of the doubts and questions that were plaguing him. At first he just wandered, but presently he realized that he had a destination in mind.

He went up a ramp and across the lobby of the United Nations Administration Building. He took a spur off the main corridor, and came to a doorway with a small circular staircase beyond it. At the bottom of the stairs he opened a steel door and stepped into the Map Room.

It was a small darkened amphitheater, with a curving row of seats along one wall. On either side were film viewers and micro-readers. And curving around on the far wall, like a huge parabolic mirror, was the Map.

Tom had been here many times before, and always he gasped in wonder when he saw the awesome beauty of the thing. Stepping into the Map Room was like stepping into the center of a huge cathedral. Here was the glowing, moving panorama of the Solar System spread out before him in a breath-taking three-dimensional image. Standing here before the Map it seemed as if he had suddenly become enormous and omnipotent, hanging suspended in the blackness of space and staring down at the Solar System from a vantage point a million miles away.

Once, Dad had told him, there had been a great statue in the harbor of Old New York which had been a symbol of freedom for strangers coming to that city from across the sea, and a welcome for countrymen returning home. And someday, he knew, this view of the Solar System would be waiting to greet Earthmen making their way home from distant stars. The Map was only an image, a gift from the United Nations to the colonists on Mars, but it reproduced the Solar System in the minutest detail that astronomers could make possible.

In the center, glowing like a thing alive, was the Sun, the hub of the magnificent wheel. Around it, moving constantly in their orbits, were the planets, bright points of light on the velvet blackness of the screen. Each orbit was computed and held on the screen by the great computer in the vault below.

But there was more on the Map than the Sun and the planets, with their satellites. Tiny green lights marked the Earth-Mars and the Earth-Venus orbit-ships, moving slowly across the screen. Beyond Mars, a myriad of tiny lights projected on the screen, the asteroids. Without the magnifier Tom could identify the larger ones ... Ceres, on the opposite side of the Sun from Mars now as it moved in its orbit; smaller Juno, and Pallas, and Vesta....

For each asteroid which had been identified, and its orbit plotted, there was a pinpoint of light on the screen. For all its beauty, the Map had a very useful purpose ... the registry and identification of asteroid claims among the miners of Mars. Each asteroid registered as a claim showed up as a red pinpoint; unclaimed asteroids were white. But even with the advances of modern astronomy only a small percentage of the existing asteroids were on the map, for the vast majority had never been plotted.

Tom moved up to the Map and activated the magnifier. Carefully he focussed down on the section of the Asteroid Belt they had visited so recently. Dozens of pinpoints sprang to view, both red and white, and beneath each red light the claim-number neatly registered. Tom peered at the section, searching until he found the number of Roger Hunter's last claim.

It was quite by itself, not a part of an asteroid cluster. He stepped up the magnification, peered at it closely. There were a dozen other pinpoints, all unclaimed, within a ten-thousand-mile radius....

But near it, nothing....

No hiding place.

And then, suddenly, he knew the answer. He stared at the Map, his heart pounding in his throat. He cut the magnification, scanning a wide area. Then he widened the lens still further, and checked the coordinates at the bottom of the viewer.

He knew that he was right. He had to be right. But this was no wild dream, this was something that could be proved beyond any question of error.

Across the room he picked up the phone to Map Control. It buzzed interminably; then a sleepy voice answered.

"The Map," Tom managed to say. "It's recorded on time-lapse film, isn't it?"

"'Course it is," the sleepy voice said. "Observatory has to have the record. One frame every hour...."

"I've got to see some of the old film," Tom said.

"Now? It's three in the morning."

"I don't need the film itself, just project it for me. There's a reader here."

He gave the man the dates he wanted, Mars time. The man broke the contact, grumbling, but moments later one of the film-viewers sprang to life. The Map coordinates showed at the bottom of the screen.

Tom stared at the filmed image ... the image of a segment of the Asteroid Belt the day before Roger Hunter had died.

It was there. When he had looked at the Map, he had seen a single red pinpoint of light, Roger Hunter's asteroid, with nothing in the heavens anywhere near it.

But on the film image taken weeks before there were two points of light. One was red, with Roger Hunter's claim number beneath it. The other was white, so close to the first that even at full magnification it was barely distinguishable.

But it was there.

Tom's hands were trembling with excitement; he nearly dropped the phone receiver as he punched the buttons to ring the apartment. Greg's face appeared on the screen, puffy with sleep. "What's that? Thought you were in bed...."

"You've got to get down here," Tom said.

Greg blinked, waking up. "What's the matter? Where are you?"

"In the Map Room. Wake Johnny up and get down here. And try to get hold of the Major."

"You've found something," Greg said, excited now.

"I've found something," Tom said. "I've found where Dad hid his strike ... and I know how we can find it! We've got the answer, Greg."