The monster ground to a halt amid the wreckage. Then its engine bellowed with sudden power and it spun half round, one tread spraying gravel, and backed hastily away up the slope. And Dworn was aware that the noise of creaking treads had redoubled. He cast about, and saw, laboring upward from below, another big machine, closely similar to the first. Both scavengers came to a stop, facing one another across the fading of the fires, their unmuffled engines grumbling sullenly. Dworn watched them narrowly, expecting the shooting to begin any moment. But the scavengers' way of life was not one that encouraged reckless valor. After a long minute, a hatch-cover was lifted in the first arrival's armored back; a cautious head thrust forth, and shouted hoarsely, words clear to Dworn's amplified hearing: "Better go back where you came from, brother. We got here first!" The other scavenger's turret-hatch also swung slightly open. A different voice answered: "Don't talk foolishness, brother. We've got as much right here as you, and anyway we _saw_ it first!" The first voice thickened with belligerence. "We've got the advantage of the ground on you, brother. Better back up!" "Oh, go smelt pebbles!" snarled the other. No doubt that was a scathing rejoinder among the scavengers. * * * * * Dworn grimaced scornfully and brought his turret-gun to bear on an outcropping midway between the disputants. Either of them outweighed the little beetle twenty times over--but at this juncture a single unexpected shot would probably send both of them scuttling for cover-- But he halted again on the verge of firing. For he had not stopped listening, and now his trained ears picked out another, an unfamiliar sound from the background of noises. It was a queer rattle and scurry, mingled with a high-pitched buzz that could only come from a number of small but high-speed motors. It was not a sound the exact like of which Dworn remembered having heard before. He went rigid, staring, as the sound's source came into view. A column of little machines--lighter even than a beetle, and more elongated--advancing in single file, multiple wheels swerving in the leader's tracks as the column wound nearer along the mountainside. As the firelight fell on them they gleamed with the mild sheen of aluminum. Round vision-ports stared glassily, and turbines buzzed feverishly shrill. With astonishing bravado, the flimsy little vehicles, one behind another, came parading onto the wreck-strewn slope. And what was more startling still--no two of them were alike. The leader mounted a winch in plain view; behind came another machine fitted with oddly-shaped grappling claws, and next one bearing a mysterious device terminating in front in a sort of flexible trunk.... Strangely, too, they didn't seem to carry any armament--no snouting guns, no flame or gas projectors. Despite that fact or perhaps because of it, something sounded an alarm deep in Dworn's mind.