I heard Srtes beside me sigh heavily as he rose to his feet. "Do you realize," he asked no one in particular, "that he is already half-way through? All our calculations pointed to the odds being heavily against his reaching this far." "The sentinels will find him in a few minutes," one of the councilors said reassuringly. "Of course they will!" Srtes replied angrily. "But he was not supposed to be able to get this far." * * * * * The alien stayed beneath the ramp only until his pursuers ran past. Immediately after, he reappeared and strode without hesitation toward the nearest air vent. The screen stuck when he gripped its spokes and tried to turn it, but he exerted his strength and it gave slowly. He pulled it from its frame and let it rest on the floor. Pushing his feet through the vent opening, still clutching the screen, he let himself down. Soon his feet came to rest on the inside ledge of the air tunnel and he balanced there as he screwed the screen back into place. He had vanished by the time the sentinels came running back. "By the great hound of Hagras!" a councilor exclaimed. "Is there no end to the creature's ingenuity?" None of us paid any attention to him; we were too busy watching the scene below. Only Srtes spoke. "Will the fools have brains enough to look for him down there?" he muttered. The excitement of the chase had obviously gripped him also. He clicked on a control button that split the screen into two scenes, and we were able to watch the activity above, as well as in the tunnels below. We had no trouble following the flight of the alien. The lining of the tunnels had been prepared with a luminous coating that gave enough light for us to see the inside clearly. As we watched, the alien stumbled and fell to the floor. He lay for a long moment, too weary to rise. By this time he must be exhausted. His stamina had already proven greater than we had anticipated. He rose again and walked doggedly on, searching absent-mindedly in his pockets as he went. I knew he must be hungry and thirsty. He was probably only now remembering the packet he had lost early in his flight. But he did not slow his steady progress forward. On the right half of the screen we noted that the captain of the sentinels had evidently figured out what had happened. Up ahead his men were hurrying into the numerous branches of the air tunnel and blocking every passage. As they had probably been ordered, they began walking slowly back. We kept our attention on the one who would intercept the fugitive. The alien stopped occasionally and stood listening. Once he paused longer than usual. Was his hearing that good, I wondered, or was he just being cautious? After a minute he moved forward again, until only a fairly long bend in the tunnel branch separated him from the oncoming sentinel.