During the early centuries of the Atomic Era, he knew, there had been great wars, the stories of which had survived even to the Hundredth Century. Among the weapons that had been used, there had been artificial plagues and epidemics, caused by new types of bacteria developed in laboratories, against which the victims had possessed no protection. Those germs and viruses had persisted for centuries, and gradually had lost their power to harm mankind. Suppose, now, that he had brought some of them back with him, to a century before they had been developed. Suppose, that was, that he were a human plague-carrier. He thought of the vermin that had infested the clothing he had taken from the man he had killed on the other side of the mountain; they had not troubled him after the first day. There was a throbbing mechanical sound somewhere in the air; he looked about, and finally identified its source. A small aircraft had come over the valley from the other side of the mountain and was circling lazily overhead. He froze, shrinking back under a pine-tree; as long as he remained motionless, he would not be seen, and soon the thing would go away. He was beginning to understand why the search for him was being pressed so relentlessly; as long as he remained alive, he was a menace to everybody in this First Century world. He got out his supply of food concentrates, saw that he had only three capsules left, and put them away again. For a long time, he sat under the dying tree, chewing on a twig and thinking. There must be some way in which he could overcome, or even utilize, his inherent deadliness to these people. He might find some isolated community, conceal himself near it, invade it at night and infect it, and then, when everybody was dead, move in and take it for himself. But was there any such isolated community? The farmhouse where he had worked had been fairly remote, yet its inhabitants had been in communication with the outside world, and the physician had come immediately in response to their call for help. The little aircraft had been circling overhead, directly above the place where he lay hidden. For a while, Hradzka was afraid it had spotted him, and was debating the advisability of using his blaster on it. Then it banked, turned and went away. He watched it circle over the valley on the other side of the mountain, and got to his feet. 4 Almost at once, there was a new sound--a multiple throbbing, at a quick, snarling tempo that hinted at enormous power, growing louder each second. Hradzka stiffened and drew his blaster; as he did, five more aircraft swooped over the crest of the mountain and came rushing down toward him; not aimlessly, but as though they knew exactly where he was. As they approached, the leading edges of their wings sparkled with light, branches began flying from the trees about him, and there was a loud hammering noise.