The end of the corridor no longer opened out into the moonlit square of ruined Nan-Tauach. It was barred by a solid mass of glimmering stone. The moon door had closed! O'Keefe took a stumbling step toward the barrier behind us. There was no mark of juncture with the shining walls; the slab fitted into the sides as closely as a mosaic. "It's shut all right," said Larry. "But if there's a way in, there's a way out. Anyway, Doc, we're right in the pew we've been heading for--so why worry?" He grinned at me cheerfully. The man on the floor groaned, and he dropped to his knees beside him. "Marakinoff!" he cried. At my exclamation he moved aside, turning the face so I could see it. It was clearly Russian, and just as clearly its possessor was one of unusual force and intellect. The strong, massive brow with orbital ridge unusually developed, the dominant, high-bridged nose, the straight lips with their more than suggestion of latent cruelty, and the strong lines of the jaw beneath a black, pointed beard all gave evidence that here was a personality beyond the ordinary. "Couldn't be anybody else," said Larry, breaking in on my thoughts. "He must have been watching us over there from Chau-ta-leur's vault all the time." Swiftly he ran practised hands over his body; then stood erect, holding out to me two wicked-looking magazine pistols and a knife. "He got one of my bullets through his right forearm, too," he said. "Just a flesh wound, but it made him drop his rifle. Some arsenal, our little Russian scientist, what?" I opened my medical kit. The wound was a slight one, and Larry stood looking on as I bandaged it. "Got another one of those condensers?" he asked, suddenly. "And do you suppose Olaf will know enough to use it?" "Larry," I answered, "Olaf's not outside! He's in here somewhere!" His jaw dropped. "The hell you say!" he whispered. "Didn't you hear him shriek when the stone opened?" I asked. "I heard him yell, yes," he said. "But I didn't know what was the matter. And then this wildcat jumped me--" He paused and his eyes widened. "Which way did he go?" he asked swiftly. I pointed down the faintly glowing passage. "There's only one way," I said. "Watch that bird close," hissed O'Keefe, pointing to Marakinoff--and pistol in hand stretched his long legs and raced away. I looked down at the Russian. His eyes were open, and he reached out a hand to me. I lifted him to his feet. "I have heard," he said. "We follow, quick. If you will take my arm, please, I am shaken yet, yes--" I gripped his shoulder without a word, and the two of us set off down the corridor after O'Keefe. Marakinoff was gasping, and his weight pressed upon me heavily, but he moved with all the will and strength that were in him.