"It seems rather a weird idea," I said, "but I can see nothing so horrible about it."

"It is not the idea that is horrible," she said; "it is the method that he employs to perfect his invention. In his effort to duplicate the human brain, he must examine it. For this reason he needs many slaves. A few he buys, but most of them are kidnaped for him."

She commenced to tremble, and her voice came in little broken gasps. "I do not know; I have not really seen it; but they say that he straps his victims so that they cannot move and then removes the skull until he has exposed the brain; and so, by means of rays that penetrate the tissue, he watches the brain function."

"But his victims cannot suffer long," I said; "they would lose consciousness and die quickly."

She shook her head. "No, he has perfected drugs that he injects into their veins so that they remain alive and are conscious for a long time. For long hours he applies various stimuli and watches the reaction of the brain. Imagine if you can, the suffering of his poor victims.

"Many slaves are brought here, but they do not remain long. There are only two doors leading from the building, and there are no windows in the outer walls.

"The slaves that disappear do not leave through either of the two doorways. I see them today; tomorrow they are gone, gone through the little doorway that leads into the room of horror next to Fal Sivas's sleeping quarters.

"Tonight Fal Sivas sent for two of us, another girl and myself. He purposed using only one of us. He always examines a couple and then selects the one that he thinks is the best specimen, but his selection is not determined wholly by scientific requirements. He always selects the more attractive of the girls that are summoned.

"He examined us, and then finally he selected me. I was terrified. I tried to fight him off. He chased me about the room, and then he slipped and fell; and before he could regain his feet, I opened the door and escaped. Then I heard the other girl scream, and I knew that he had seized her, but I have won only a reprieve. He will get me; there is no escape. Neither you nor I will ever leave this place alive."

"What makes you think that?" I inquired.

"No one ever does."

"How about Rapas?" I asked. "He comes and goes apparently as he wishes."

"Yes, Rapas comes and goes. He is Fal Sivas's assassin. He also aids in the kidnaping of new victims. Under the circumstances he would have to be free to leave the building. Then there are a few others, old and trusted retainers, really partners in crime, whose lives Fal Sivas holds in the palm of his hand; but you may rest assured that none of these know too much about his inventions. The moment that one is taken into Fal Sivas's confidence, his days are numbered.