The sixth rocket man came through the door boldly enough—and suddenly leaped toward the side of the chamber where another door was. His hands were jolting at the locked barrier when the rifles sounded. A violent blast of greenish-yellow explosion rocked the chamber and shook the floors beyond. When it cleared, the Alien was dust and vapor, with nothing that could be studied for evidence.

Two workers who had been standing in line in a building beyond broke through the seal together, without waiting their turn, and headed with desperate haste for the shelter of a nearby barracks. A rifle bullet tore into one, and both exploded instantly.

By the time the rest had been proved safe in a testing ordeal as grim as death, it was the hour for lunch—a shocked, silent interlude at first. Then one of the men caught sight of a neighbor busily shaking his fork, and glancing sideways to emphasize some point. A tiny gadget appeared, and was concealed quickly under the steak on the man's plate. Ten seconds later, when the man cut into the meat, there was a cowlike bellow and the meat leaped six inches up, and two feet sideways. There was a shout of laughter that grew into a roar, and everything was suddenly normal again.

Norden shook his head. The incident appeared grotesque to him. Fluoroscope or not, something was wrong with him. He couldn't have been so different from other men before the ordeal on Hardwick's asteroid. That ruined steak had cost a small fortune to transport from Earth, and the man would lose valuable time while waiting for another to be cooked. And yet, Norden could see that somehow it had been effective therapy, had relieved an almost intolerable tension.

They spent the afternoon sending out the test "balloon" rockets with the various elements of Hardwick's screen. On the way back to the barracks, Norden noticed there were now six guards stationed about the laboratory, two of whom instantly fell into step behind him. He had been shifted to the dormitory over the Headquarters building, where he would be in the least danger—and also have the least freedom from observation!

But he forgot it the next day as the results of the tests came in. The shields had been completely ineffective. Dead rabbits still were unmolested, but live ones had been picked off in everything they had sent out.

Miles accepted the result with a despairing shrug, but Pat was hit hard by it. None of the other research teams seemed to be getting anywhere. There was no way to detect Aliens, and no way to screen humans.

On the fourth day, when the last possible variation of Hardwick's formula had proved useless, and the Aliens had moved their lines up to fifty million miles from Earth's orbit, Pat was down early, re-checking the translation the computer had made. Norden came in, saw the results, and swore.

For three hours, he pored over the Japanese scientist's mathematics—and as before, he found his mind reaching for something, only to begin some useless side speculation that threw him off. It was as if he had a censor in his mind telling him he could go no further. He considered the grim prospect of ten days or more of life for himself, and the men here, until the noonday signal sounded.

Somebody had put a new plastic glue on the handle of his knife and fork, and it was fifteen minutes before he could locate a solvent that removed it. Pat laughed at his plight along with the others. He checked his anger, swallowed it—and suddenly realized that in a strange way, the practical jest played on him was a mark of acceptance.