Concrete baffles four feet thick lay on the other side and Benton visualized the quick turns he would have to take after he swung open the final door. Time was running out and there wouldn't be another chance; if Benton failed, Urei would be forever on the alert against him--if, indeed, Urei didn't operate on the man's brain forthwith. There was no hesitation with the key to the second door. It was a large one and quite distinctive. Benton separated it from the others and inserted it in the elongated slot at the left side of the heavy grey door. He turned it sharply, but it resisted. Forcing himself to go slowly he backed it around and tried again. It didn't turn. He took it out, looked at it again, then gave it another try. This time he acted deliberately, certain that the key was inserted properly, but he may as well have used the wrong key, for all the good it did. Abruptly he stepped back, his face a livid, gargoylish mask. This time he knew where his trouble was. "You're here!" he accused, speaking to the door. 5 The voice that answered in Benton's brain was gentle. "I didn't mean to punish you that way," it said; "I was busy. But if you remember, I told you I could exist without that building full of electronic apparatus. It was you who assumed I was a liar, you know; I gave you no evidence for the assumption. Look at that key." Benton was dazed. He seemed to have lost all his drive, his determination to wreck Urei. A reaction was setting in; his hand trembled weakly as he reached for the key and removed it from the slot. He looked at it dully, then let his eyes rest on the bunch from which he had removed it. The large, distinctive key was still with the bunch. The one in his shaking hand was smaller, entirely dissimilar. "It was better that I let you go this far, anyway," came the silent mental voice. "I was going to let you see this room, sooner or later. Go on in." Benton's eyes opened a bit wider, but still held the dazed look. The door was swinging wide, by itself. Almost stumbling, he felt his way through the maze of baffles, heedless of the fact that the further he went the more he exposed himself to the deadly, hard rays generated by the pile. Without armor, Benton had intended to enter swiftly, throw the master switch which would kill the pile, then retreat as fast. Now, however, he didn't even think of it. His brain was dulled by defeat after those many hours of rigid control which had been so useless. But it didn't matter; the pile was already dead. "This pile was self-maintaining," the voice explained. "It never needed attention, and if something went wrong it would have warned everybody within miles with the sirens. So it's no wonder that nobody ever discovered that I killed it years ago. The thing made me nervous, being so close."