narrowly at the Martian, and its mouth opened and closed nervously. There was a faint something in its almost blank face which suggested to the Earthman that the bond of friendship between the Prince of Selba and this weird devil of the void was none too strong.

Hekalu withdrew his arm from about the girl. He nodded toward the bejeweled nightmare. "I had almost forgotten my lieutenant here, Mr. Shelby," he said. "He is the ruler of the empire from which I am recruiting my forces—my chief ally. Since his people do not employ a language of sounds, he has no vocal name; but for the sake of convenience I have christened him Alkebar, which means 'The Unknown.' He was my companion on my recent trip to Earth, for he wanted very much to see what a beautiful place is your world." There was a sinister hint in these last words.

Hekki made a few quick signs to Alkebar with his fingers, and then turned to the girl. "I must ask you two to leave us now, Jan," he said. "Mr. Shelby and I have an important matter to discuss."

Alkebar grasped Janice's arm with a horny paw, and hurried her through the door. But nevertheless Shelby caught a fleeting glimpse of her face as her lips formed, but did not utter, the word—"Wait." Hekki did not see.

The Earthman turned upon the Martian. "I am going to usurp your assumed right to start this little private conversation, Akar Hekalu," he told him. "There is only one thing I have to say. You are a noble, the son of a long line of nobles who righted wrongs and avenged insults on the field of honor. You have wronged me, no you have outraged me. Therefore I challenge you to combat. Choose your weapons. No place will suit me better than this room; no time better than now." But if Austin had expected to nettle Hekalu into a mood for fighting, he was disappointed.

The Martian was smiling mockingly. "Life is sweet," he said, "sweeter to me than it has ever been before. I do not wish to die—not even by your hands. And you—you have certain knowledge and information which is valuable to me. You must live. I was going to talk to you about what you know. That weapon of yours—we are working on a projector. But something is evidently missing—a tiny element."

"What you have learned about the Atomic Ray," Shelby cut in, "you learned through your own efforts. If you can steal the remainder of the necessary information from my brain, you are welcome. Otherwise, I urgently invite you to go to the devil."

Hekki's face assumed a look of infinite though make-believe sadness. It was a trick such as a designing woman might use to attract some desirable male.

"I am sorry to hear you talk so, Mr. Shelby," he said. "But as you suggest, I believe that there are ways of stealing knowledge even from your mind. For instance, in an old vault beneath my palace at Taboor, I once found a sealed vat containing a certain fluid. The Ancient Ones were wise, for when they desired any man to talk, they thrust his arms or his legs, or perchance his whole body into the fluid. Very slowly, and with some discomfort, it ate away the tissue of his nerves. I must leave you now, my friend. Think well, and may the gods that rule the universe guide you on the right course."

He opened the door. Shelby caught a glimpse of a long hall, and at the far end, the bewildering maze of control-room equipment. The panel closed.