"Antigrav!" Borton leaned nearer to the edge. "They have antigrav in small mobile units."

Antigrav we knew. But the principle could not be used in mobile units, only installed in buildings as a method of transport from floor to floor. Here these carriers, loaded with heavy burdens, swung along in ordered lines through a dark archway in the opposite wall.

"Where's the controller?" The other Patrolman peered over.

"Remote control, I would say." Foss stood up.

We had all fallen flat at the sign of the activity. But now Foss apparently thought we had nothing to fear. And a moment later he added:

"Those are programmed robos."

Programmed robos! The complexity of the operation here on Sekhmet increased with every discovery we made. Programmed robos were not ordinarily ship workers, like the controlled ones we had earlier seen and used ourselves. They were far more intricate, requiring careful servicing, which made them impractical for use on primitive worlds. One did not find them on the frontier. Yet here they were at work light-years away from the civilizations producing them. Shipping these here, preparing them for work, would have been a major task in itself.

"In a jack hideout?" Foss protested.

"Look closer!" Borton was still watching below. "This is a storehouse which is being systematically looted. And who would have situated it here in the first place—"

"Forerunners," Lidj answered him. "But machines —this is not a tomb, nor—"

"Nor a lot of things!" Borton interrupted. "There were Forerunner installations found on Limbo. The only difference is that those were abandoned, not stored away. Here—perhaps a whole civilization was kept—both men and machines! And the Forerunners were not a single civilization, either—even a single species. Ask the Zacathans—they can count you off evidence of perhaps ten which have been tentatively identified, plus fragments of other, earlier ones which have not! The universe is a graveyard of vanished races, some of whom rose to heights we cannot assess today. These machines, if they can be made to work again, their purposes learned—"

I think that the possibilities of what he said awed us. Of course, we all knew of such treasure hunting as had been indulged in on Thoth—that was common. Lucky finds had been made all around the galaxy from time to time. The Zacathans, that immensely old, immensely learned reptilian race whose passion was the accumulation of knowledge, had their libraries filled with the lore of vanished—long-vanished—stellar civilizations. They led their archaeological expeditions from world to world seeking a treasure they reckoned not in the furnishings of tombs, in the hidden hoards discovered in long-deserted ruins, but in the learning of those who had left such links with the far past.

And parties of men had made such finds also. They had spoken of Limbo—that had been the startling discovery of a Free Trader in the earlier days.

Yet the plunder from here had not yet turned up on any inner-planet market, where it would logically be sold. Its uniqueness would have been recognized instantly, for rumor of such finds spreads quickly and far.

"Suppose"—Foss, plainly fascinated, still watched the antigravs floating in parade order out of the storeroom—"the jacks, even the Guild, began this. But now it has been taken over by those others."

"Yes," came the dry, clipped answer from Lidj. "It could be that the original owners are now running the game." He raised both hands to his bald skull, rubbed his fingers across it. There was still a mark on his forehead from the weight of the crown.

"You mean—" Borton began.

Lidj turned on him. "Is that so strange? We put men in stass-freeze for years. In fact I do not know what has been the longest freeze time ending in a successful resuscitation. These might be awakened to begin life at the point where they left off, ready for their own plan of action. Do you deny that they have already proved they have secrets which we have not? Ask your own man, Harkon—how can he explain what has happened to the three of us?"

"But the others stored here—at least that one in the box above the valley—was dead." My protest was weak, because too much evidence was on Lidj's side.

"Perhaps most of them did die, perhaps that is why they want our bodies. Who knows? But I will wager that they—those three who took ours—are now in command of this operation!"

Harkon had drawn a little apart, perilously close to the edge of the balcony. Now he spoke in the same husky tone our cargomaster used.

"Can you set an interrupt beam on these lasers you have?" I did not understand what he meant, but apparently his question made sense to Borton, who joined him.

"Tricky—from here," the commander observed.

"Tricky or not, we can try it. Let me see yours—"

Did Borton hesitate for a moment before he passed over that weapon? If so, I could understand, since lurking at the back of my mind was a shadowy suspicion of these three. It is never easy to accept body exchange, even for one knowing the Thassa.

But Borton appeared willing to trust the pilot and passed over the laser. Harkon squatted against the sharply sloping wall, which made him hunch over the weapon. He snapped open the charge chamber, inspected the cartridge there, closed it once more, and reset the firing dial.

With it in his hand he went to peer down, selecting a victim. There was a robo to his left, now engaged in shifting a metal container onto one of the waiting transports. Harkon took aim and pressed the firing button.

A crackle of lightning sped like a whiplash, not to touch the robo itself, but to encircle its knoblike head. The robo had a flexible tentacle coiled about the container, ready to swing it across to the platform. But that move was never completed. The robo froze with the container still in the air.

"By the Teeth of Stanton Gore, you did it!" Borton's voice was almost shrill.

The pilot wasted no time in waiting for congratulations on his skill. He had already aimed at the next robo and stopped that one dead also.

"So you can knock them out," Lidj observed. "What do we do now—" Then he paused and caught at Borton's arm. "Is there a chance of resetting them?"

"We can hope so."

The robos I knew and had always used were control ones. Free Traders visited only the more backward worlds where machines were simple if used at all. I had no idea how one went about reprogramming complex robos. But the knowledge of a Free Trader was not that of a Patrolman. Plainly Borton and Harkon hoped the machines could be made to work in some manner for us.

Which is what they proceeded to find out. When the six robos were halted we came down from the balcony. The antigrav transports still moved at a slow and even pace, though those now edging away were only partly loaded. Foss and the other Patrolman went into action, turning their lasers with less precision but as great effect on the motive section of those. The carriers crashed to the floor with heavy jars which shook even this rock-walled chamber.

The Patrolmen gathered about the nearest robo. Harkon was already at work on the protective casing over its "brain." But I was more interested in the transports. Basically these were nothing more than ovals of metal, with low side walls to hold their loads in place. The motive force of each lay in a box at the rear. The principle of their construction was unlike anything I had ever seen before.

"Something coming!" At that warning from Griss we all went to ground. But what loomed into view out of the opening was an empty transport back for another load. Foss had raised his laser to short it when Lidj jerked at his arm to spoil his aim.

"We can use that!" He made a running jump, caught" the edge of the carrier's wall, and swung up on it. It did not halt its forward movement, proceeding steadily down a row of boxes until it came to a stop beside a motionless robo, still holding a crate aloft between clawed appendages.