the race that built this place had reached approximately a grade C-5 of civilization, according to the Mokart scale. This apparently was their council chamber."

"What are those rectangular stone blocks depending from the ceiling?" I said.

Mason turned the light beam upward. "I don't know," he said. "But my guess is that they are burial vaults. Perhaps the creatures were ornithoid."

Away from the flash the floor of the plaisance appeared to be a great mirror that caught our reflections and distorted them fantastically and horribly. We saw then that it was a form of living mold, composed of millions of tiny plants, each with an eye-like iris at its center. Those eyes seemed to be watching us, and as we strode forward, a great sigh rose up, as if in resentment at our intrusion.

There was a small triangular dais in the center of the chamber, and in the middle of it stood an irregular black object. As we drew nearer, I saw that it had been carved roughly in the shape of this central building and that it was in a perfect state of preservation.

Mason walked around this carving several times, examining it curiously.

"Odd," he said. "It looks to be an object of religious veneration, but I never heard before of a race worshipping a replica of their own living quarters."

Suddenly his voice died off. He bent closer to the black stone, studying it in the light of the powerful ato-flash. He got a small magnifying glass out of his pocket and focused it on one of the miniature bas-reliefs midway toward the top of the stone. Unfastening his geologic hammer from his belt, he managed, with a sharp, swinging blow, to break off a small protruding piece.

He drew in his breath sharply, and I saw his face go pale. I stared at him in alarm.

"What's wrong?" I asked.

He motioned that I follow and led the way silently past the others toward the stair shaft. Climbing to the top level was a heart-pounding task, but Mason almost ran up those steps. At the surface he leaned against a pillar, his lips quivering spasmodically.

"Tell me I'm sane, Bagley," he said huskily. "Or rather, don't say anything until we've seen Norris. Come on. We've got to see Norris."

All the way back to the Marie Galante, I sought to soothe him, but he was a man possessed. He rushed up the ship's gangway, burst into central quarters and drew up before Navigator Norris like a runner stopping at the tape.

"You damned lying hypocrite!" he yelled.

Norris looked at him in his quiet way. "Take it easy, Mason," he said. "Sit down and explain yourself."

But Mason didn't sit down. He thrust his hand in his pocket, pulled out the piece of black stone he had chipped off the image in the cavern and handed it to Norris.

"Take a look at that!" he demanded.

Norris took the stone, glanced at it and laid it down on his desk. His face was emotionless. "I expected this sooner or later," he said. "Yes, it's Indurate all right. Is that what you want me to say?"

There was a dangerous fanatical glint in Mason's eyes now. With a sudden quick motion he pulled out his heat pistol.

"So you tricked us!" he snarled. "Why? I want to know why."

I stepped forward and seized Mason's gun hand. "Don't be a fool," I said. "It can't be that important."

Mason threw back his head and burst into an hysterical peal of laughter. "Important!" he cried. "Tell him how important it is, Norris. Tell him."

Quietly the Navigator filled and lighted his pipe. "I'm afraid Mason is right," he said. "I did trick you. Not purposely, however. And in the beginning I had no intention of telling anything but the truth. Actually we're here because of a dead man's vengeance."

Norris took his pipe from his lips and stared at it absently.

"You'll remember that Ganeth-Klae, the Martian, and I worked together to invent Indurate. But whereas I was interested in the commercial aspects of that product, Klae was absorbed only in the experimental