Hawk Carse's eyes were frigid gray mists in a graven, expressionless face as he turned to the left of the case and pulled over one of the well-remembered knife switches. A low hum came; a ghost of rosy color diffused through the liquid in the case. The color grew until the whole was glowing jewel-like in the dim-lit laboratory, and the narrow tubes leading into the undersides of the brains were plainly visible. Something within the tubes pulsed at the rate of heart-beats. The stuff of life. When the color ceased to increase, Carse pulled the second switch, and moved close to the grille inset in a small panel above the case. Slowly, gently he said into the grille: "Master Scientist Cram, Professors Estapp and Geinst, Doctors Swanson and Norman--I wish to talk to you. I am Captain Carse, friend of Master Scientist Eliot Leithgow. Some days ago you aided us in our escape from here, and in return I made you a promise. Do you remember?" There was a pause, a silence so tense it was painful. And then functioned the miracle of Ku Sui's devising. There came from the grille a thin, metallic voice from the living dead. "_I remember you, Captain Carse, and your promise._" * * * * * A voice from living brain cells, through inorganic lungs and throat and tongue! A voice from five brains, speaking, for some obscure reason which even Ku Sui could not explain, in the first person, and setting to mechanical words the living, pulsing thoughts that sped back and forth inside the case and were coordinated into unity by the master brain, which had once been in the body of Master Scientist Cram. A voice out of nothingness; a voice from what seemed so clearly to be the dead. To Hawk Carse, man of action, it was unearthly; it was a miracle the fact of which he could not question, but which he could not hope to understand. And well might it have been unearthly to anyone. Even to-day. Still thrilling to the wonder of it, he went on: "I have returned here to the asteroid with friends. Primarily I came to keep my promise to you, but I intend to do more. Dr. Ku Sui is not here now, and will not be for at least fifteen minutes; but when he does return, I am going to capture him. I am going to take him alive." He was silent for a moment. "Perhaps you do not know," he continued levelly, "but the people of Earth hold Master Scientist Eliot Leithgow responsible for your disappearance. He is therefore a fugitive, and there is a price on his head. It is my purpose to restore Eliot Leithgow to his old place by returning Dr. Ku to Earth to answer for the crimes he has effected on you. "I am now ready to fulfil my promise to you. I expect no interruption this time. I regret exceedingly my inability to destroy you when I was here before, but I simply could not in the little time I had. I still do not know how best to go about it. Perhaps you will tell me. I will wait...." An afterthought came to him. He added into the grille: