It was of metal. It seemed to be a model in gleaming steel of a problem in solid geometry: it was an angular small cage, an inch wide by perhaps three and a half inches square. That is, at first it seemed square. But a closer look revealed that no two corresponding sides of the little cage were quite parallel. Each angle, each line was subtly different. Doctor Satan pointed it at the library wall. The end he pointed was a trifle wider than the end heeled in the palm of his hand. On this wider end was one bar that was fastened only at one end. The red-covered fingers moved this bar experimentally, slowly, so that it formed a slightly altered angle with the sides.... The library wall was mist, then nothingness. The street outside was not a street. A barren plain stood there, strewn with rocky shale, like a landscape on the moon. The little bar was moved back, and the library wall was once more in place. A chuckle came from the red-masked lips; a sound that would have made a hearer shiver a little. Then it changed to a snarl. "Perfect! But again Ascott Keane interferes. This time I've got to succeed in removing him. An exploded heart...." He put the mysterious small cage back in the gold-link purse, and opened the desk drawer. From it he took a business letterhead. It was a carbon copy, with figures on it. "Bostiff...." On the rear terrace the legless giant stirred at the call. He moved on huge arms to the door and into the library.... * * * * * In his tower suite, Keane paced back and forth with his hands clasped behind him. Beatrice Dale watched him with quiet, intelligent eyes. He was talking, not to her, but to himself; listing aloud the points uncovered since his arrival here. "A few seconds after talking with Madame Sin, Weems was stricken. Also, the lady with the odd name was seen coming from the roulette room at about the time when a party entered and found the croupier and eight guests turned from people into statues. But she was nowhere around when Wilson died in the conference room." He frowned. "The watches were taken from all the sufferers from this strange paralysis, save Weems. By whom? Madame Sin? Weems' watch is absolutely in good order, but it won't run. The ball on the roulette wheels stays on a slant instead of rolling down into a slot as it should when the wheel is motionless. But the wheel doesn't seem to be quite motionless. It apparently moved a fraction of an inch in the forty-five minutes or so that I was in the room." "You're sure you didn't touch it, and set it moving?" said Beatrice. "Those wheels are delicately balanced." "Not that delicately! I barely brushed it with my fingers as I examined the ivory ball. No, I didn't move it. But I'm sure it did move...." There was a tap at the door. He went to it. Gest was in the corridor.