Finally he said, "I will have Koo Faya bring you writing materials, and you will describe in writing every detail of the manufacture of the missing element."

"No," replied Shelby, turning his face toward the Martian, "I haven't the ability to do that. It will be necessary for you to take me to the laboratory of the ship where I can demonstrate the process to you. It is much too delicate and complicated."

The noble's eyes wavered slightly. "Once," he said, "you tried to trick me, but I warn you that I am on guard now so do not attempt it again."

He signed to Alkebar who had been standing silently beside the open door. The giant drew a key from a pouch at his side, and kneeling, unlocked the fetter fastened about Shelby's ankle. It rattled to the floor. And at the same time the Earthian, leaning back on the bunk with arms stretching over his head, tapped sharply three times with his signet ring on the power-pipe. It seemed to be only an unconscious gesture—nervousness perhaps.

Immediately there was a terrific crash from down the passage way, followed by an agonized scream. Another crash. More screams.

Hekalu started, and then making a hurried gesture to Alkebar which indicated that he was to guard the inventor of the Atomic Ray, he drew his automatic and dashed down the corridor to investigate the disturbance. The Earthman however, was in no mood to be guarded. No longer shackled, he leaped to his feet and over to the center of the room. The great voiceless beast from the stars stood before the doorway with his long arms outstretched. He was not trying to capture the Earthman—only seeking to block his path.

But Shelby had no time to waste. Gathering himself together, he hurtled straight for the ankles of his opponent. The fact that the artificial gravity of the ship was of the same strength as that of Mars—only a trifle more than one-third that of Earth—added to the effectiveness of his plunge. The mighty-muscled Alkebar, puzzled by the unheard-of tactics of his agile though vastly weaker foe, suddenly found himself in a sprawling heap on the floor. Shelby leaped over him through the door, slammed it, and raced precipitately down the corridor.

In the meantime Hekalu Selba had reached Janice Darell's room, but when he had unlocked it and had thrust his head inside to see what the matter was, a heavy urn, deftly aimed, had crashed full into his face. Shelby saw him sprawling in the passage badly dazed, and a split second later Jan dashed from her cabin. She looked around, and when she saw Shelby coming swiftly toward her she flashed him a quick smile of triumph.

But Alkebar had wrenched the portal of the Earthman's recent prison open, and was in hot pursuit. He was tugging frantically at the pistol in his belt.

"Run, Jan, quick!—To the control room!" Austin shouted.