Dworn recognized that what bothered him was the puzzle of the unidentified little machines that had turned up on the battlefield only to be sent packing. During his yearlong solitary struggle to survive, he had developed an extra sense or two--and in the queerly confident behavior of those buzzing strangers he had scented danger, a trap.... So it happened that he was still looking on at the moment when the trap was sprung. A star, it seemed, fell almost vertically from the zenith, falling and expanding with the uncanny silence of flight faster than sound. The scavengers had no time to act. Dworn caught one faint glimpse of a winged shape against the sky, limned by the flashes that stabbed from it as it leveled out of its terrific dive. One scavenger shuddered with the force of a heavy explosion somewhere within it, and subsided, smoking. The other too staggered under crippling impacts, but ground somehow into motion, spinning and sliding crazily down the gravel slope. Then, as the first attacker's shock-wave made the very earth tremble, a second and a third plunged from the black heights, and as the last one rose screeching from its swoop the whole lower face of the hillside boomed into a holocaust of flame and oily smoke. The fleeing scavenger was gone, enveloped somewhere in an acre of fiery hell. Dworn, two hundred yards away, felt a searing breath of heat, and with a great effort controlled the impulse to whirl round and race for opener ground. He sat still, hands cramped sweating on the beetle's controls, while the sky whistled vindictively with the flight of things that circled in search of further targets. When, after a seeming eon, their screaming died away, he released held breath in a long sigh. He found himself trembling with reaction. Still he didn't stir. He was ransacking his memory for something he should be able to recall but which eluded him--a myth, perhaps, heard as a child beside the campfires of the horde-- The old men would know; Yold would have known. At thought of his father, the grief and fury rose up again in Dworn, and this time he knew the object of his vengeful anger. There was small doubt now in his mind that those flying machines which struck so swiftly and so murderously had been the beetles' attackers. But he didn't know what they were. He knew, of course, about the machines called hornets, which could fly and strike at fearful speeds like that, outracing sound. But the hornets flew only in daylight, and made no trouble for the nocturnal race of beetles. These--were something else. And more--between the deadly night-fliers and the harmless-looking aluminum crawlers he had seen, Dworn sensed some connection, some unnatured symbiosis. He had heard vague rumors about such arrangements, but had half-discounted them; any of the peoples whom he knew at first hand would have scorned to enter into alliance with an alien species.