"All right," Corriston said, a little of his raw-nerve exasperation returning. "Now I suppose you're going to tell us exactly how they kill their prey." "I don't have to tell you how they kill men," Macklin said. "You know as much about that as I do. You've been on Mars before. You've seen at least a few of the victims. You know exactly how they come up under a man when he's asleep, puncture his clothes and attach themselves. He doesn't just get nipped; the lamprene can seldom be pulled off that quickly. And when two or three of them attack you, it can be pretty horrible. They're more than just vampires; they sting. The poison is as deadly as aconite. It works a little slower, but almost immediately the victim starts to degenerate, his nerves first, and, then...." "All right, now I've heard an expert confirm it. I'd be grateful if you'll just shut up." "Lieutenant, I told you--" "Never mind, Doctor. I'm asking him to shut up." In silence they continued on, the tension between them increasing almost intolerably, their nerves becoming more and more frayed. And then, finally, it seemed to them that they could see the ship, and the great cliff wall surrounding it through the slight haziness left by the sandstorm and the vaguer haziness which distance imposes, could see the tumbled, flat slabs of rock that radiated out from it in all directions across the desert. But it was hard to be sure it was really the ship. It was perhaps only one of the many desert mirages which were far more common on Mars than they were on Earth. A man who has once looked at the bright, scarred face of a cliff wall in the Martian sunlight will remember it even in his dreams and no mirages are really necessary. He is certain to see it a second and a third time, like an after-image so indelibly imprinted on the retina of the human eye that its recurrence becomes inevitable. And yet, the running man could not have been a mirage. He was much nearer than the ship appeared to be, and he was falling and getting up and falling again in so frenzied a way that his movements bore the unmistakable stamp of reality. Corriston came to an abrupt halt. For an instant he simply stared, watching the distant figure fall to the sand for the fourth time and drag himself forward over the sand, his shoulders heaving convulsively. For an instant Corriston could not have moved if he had wanted to. The scarecrow and Drever were standing too close to him, so that the shoulders of the three men formed a compact unit, and their arms were in each other's way to such an extent that no real freedom of movement was possible. Corriston had almost to disentangle himself by sheer physical effort. Disentangle himself he finally did, turning completely about and shouting to the colonists behind him.