Nobody had ever seen an Alien--they invariably exploded to dust before they could be captured--but the horror of their senseless brutality was revealed in the hideous human corpses they left behind them. Norden had been drafted while there was still optimism. Men could build a hundred ships to the Aliens' one, equally radar-proof, free from danger of magnetic or electronic detection, and nearly invisible in space. In anything like an even battle, men were certain to win. But they soon discovered it wasn't an even battle. The Aliens had some means of detecting human ships accurately at distances of millions of miles, and blasting them with self-guided torpedoes, while remaining undetected themselves. And behind the torpedoes would come the dark globular ships to spray the wreckage with some force that left every cell utterly lifeless. Hardwick had been a quasi-scientist, mixed up with certain weird cults, who maintained a private laboratory on an asteroid near Jupiter's orbit. And in the desperation that followed the first foolish optimism, his theory that the Aliens could detect life itself, or the presence of the questionable mitogenetic rays that were supposed to radiate from nerve endings, was actually taken seriously. Surprisingly, the tests indicated that remote-controlled ships which had been completely sterilized went undetected, while ships carrying rats or other life were blasted. Norden, as the expert on all strange radiation, had been sent to work with Hardwick in attempting to devise a screen for the hypothetical life radiation. He never learned whether Hardwick was a wild genius, or an even wilder lunatic. While he was wearing Hardwick's improvised shield during one of the attempts to test it, the Aliens had landed and broken in. "What did they look like?" the psychologist asked casually--too casually, Norden felt. "Well, they--" He frowned, trying to remember, but a clamp came down over his mind. "I--I can't remember. And they did--something--to Hardwick. I--I...." Armsworth brushed the other question aside. "Never mind. You were wearing Hardwick's shield. Didn't they notice you?" Norden shook his head doubtfully. "No, I don't think they did. It's all horribly blurred. I think I jumped for the spacesuit locker when they breeched the airlock on the dome. I must have gotten into a suit, and been hidden by the locker door. And I must have run out after they took Hardwick away." At least he hadn't been hurt when the Alien bomb ruined the dome. He'd dug out the transmitter, sent the message, and then had spent the agony of waiting in trying to decipher the cryptic code in Hardwick's notebooks. They went over his account several times, but he could tell then little more. Then there were tests, some of which he could understand and answer without trouble, while others left him taut with uncertainty and etched worried lines into the face of the psychiatrist. But at last the man nodded doubtfully.