There seemed no way that men and prowlers could ever meet on common ground. They were alien to one another, separated by the gulf of an origin on worlds two hundred and fifty light-years apart. Their only common heritage was the will of each to battle.

But in the spring of one hundred and sixty-one, for a little while one day, the gulf was bridged.

Schroeder was returning from a trip he had taken alone to the east, coming down the long canyon that led from the high face of the plateau to the country near the caves. He hurried, glancing back at the black clouds that had gathered so quickly on the mountain behind him. Thunder rumbled from within them, an almost continuous roll of it as the clouds poured down their deluge of water.

A cloudburst was coming and the sheer-walled canyon down which he hurried had suddenly become a death trap, its sunlit quiet soon to be transformed into roaring destruction. There was only one place along its nine-mile length where he might climb out and the time was already short in which to reach it.