Guards came up to drive the men back to their huts, but Norden seemed to have high enough rating to stay for a while. He learned that one of the workers was missing, and that it had been his badge which the Alien had worn to enter the sleeping sections. Either the Alien had killed and destroyed the worker for his clothing or else he had been the worker! And he had been discovered forcing the lock on the sub-section of the hut where Norden had been sleeping! III The invasion of the base by the Alien had shocked them all, and few people had slept during the night. On his way to breakfast, Norden could feel the attention that was riveted on him. To the others, he was probably one of the most likely targets for whatever attack had been intended. He'd wondered about it himself, sick with a feeling of close disaster; but he could find no logical basis for the fear. Miles waited until they had finished with their food, his own face a study in grim anxiety. Then he stood up, and faced them. "No work this morning," he announced. "There's going to be a fluoroscopic test of every person on the base!" Norden felt a wrench at his mind that left his thoughts spinning. He caught himself, just as he heard a gasp from Armsworth, a few places down. But Miles went on as if nothing had happened. "The guards have already been checked. They'll lead us all down to the explosive test chamber. We'll go in, one at a time, and stand on a marked square. The fluoroscope results will show on a television screen visible to all of us. If you pass, you'll go across the chamber to the cleared rooms beyond. "Any man resisting or proven non-human will be shot at once. The Alien last night _looked_ human, but he didn't breathe oxygen, so his internal structure must be different. However, if anyone wants to declare that he's an Alien, he'll be treated as a prisoner of war instead of a spy." Nobody made such a declaration, and Miles nodded to the guards who had filed in, while fear-ridden faces were still staring at their neighbors. Norden wondered how long a confessed Alien would last before the men tore him to bits. Discounting hate was fine at long range--but not when the danger was at your elbow. Miles and Pat went into the chamber first, with the expected result--human skeletons and shadowy organs showing up on the screen. Norden stared in fascination, while fear built up tensions inside him. Armsworth passed in and found his position, with a face that was somehow both taut and frozen. The guards took a look at the screen and waved him on. He half staggered to the exit, his features distorted with an emotion that was unreadable.