Gentle Marene was next when the black space cruiser called for its youth-levy. If only Zurk would spark to life - Zurk, this huge, part-human war machine of tubular steel muscles and blank, mechanical mind.

There was both agony and defeat etched deeply into Guyard's lean face as he stood there in the center of the hidden attic laboratory. His fists were clinched tightly at his sides and his hollow eyes were staring tensely and with supplication at the steel monstrosity before him.

"Zurk, you must save her!" he pleaded. "You must save Marene!"

Zurk, the man of steel, made no move. He sat there expressionless, his electric-cell eyes staring out through the small window at the far end of the laboratory.

Year after year, the steel giant had sat there staring through that window, staring out into dim, perpetual daylight that always enveloped that half of the moon which kept its face constantly toward Jupiter.

Week after week and month after month, Guyard had stood before the giant, had stood there hurling thought-waves into the brain, but to no avail. Something was wrong somewhere within the intricate mechanism, some trouble he could not locate.

Nervous and shaken, he stood there glaring into the expressionless eyes. There were but a scant two weeks left. Then the evil creatures from the Land of Darkness on the other side of the moon would come to claim Marene.

Desperation gave power to Guyard's tired brain. "Zurk!" His eyes blazed into the giant's with a final effort. "Move your head!"

For a brief instant, Guyard was certain that a feeble thought-wave had tried to penetrate his own brain; he thought he caught a faint glow in the eyes.

Then he wheeled quickly at the sound of a step upon the ladder up to the trapdoor in the floor. His hand flashed to the gun at his belt, and he waited tensely.