Schwartzmann's thoughts had come back to the matter of air; he motioned Chet and Harkness toward the port. Diane Delacouer had joined them and she thrust herself quickly between the two men. And, though Schwartzmann made a movement as if he would snatch her back, he thought better of it and motioned for the portal to be swung. Chet felt him close behind as he followed the others out into the gathering dark. * * * * * The air was heavy with the fragrance of night-blooming trees. They were close to the edge of the lava flow. The rock was black in the light of a starry sky; it dropped away abruptly to a lower glade. A stream made silvery sparklings in the night, while beyond it were waving shadows of strange trees whose trunks were ghostly white. It was all so familiar.... Chet smiled understandingly as he saw Walt Harkness' arm go about the trim figure of Diane Delacouer. No mannish attire could disguise Diane's charms; nor could nerve and cold courage that any man might envy detract from her femininity. Her dark, curling hair was blowing back from her upraised face as the scented breezes played about her; and the soft beauty of that face was enhanced by the very starlight that revealed it. It was here that Walt and Diane had learned to love; what wonder that the fragrant night brought only remembrance, and forgetfulness of their present plight. But Chet Bullard, while he saw them and smiled in sympathy, knew suddenly that other eyes were watching, too; he felt the bulky figure of Herr Schwartzmann beside him grow tense and rigid. But Schwartzmann's voice, when he spoke, was controlled. "All right," he called toward the ship; "all iss safe." Yet Chet wondered at that sudden tensing, and an uneasy presentiment found entrance to his thoughts. He must keep an eye on Schwartzmann, even more than he had supposed. Their captor had threatened to maroon them on the Dark Moon. Chet did not question his intent. Schwartzmann would have nothing to gain by killing them now. It would be better to leave them here, for he might find them useful later on. But did he plan to leave them all or only two? Behind the steady, expressionless eyes of the Master Pilot, strange thoughts were passing.... * * * * * There were orders, at length, to return to the ship. "It is dark already," Schwartzmann concluded; "nothing can be accomplished at night. "How long are the days and nights?" he asked Harkness. "Six hours." Harkness told him; "our little world spins fast." "Then for six hours we sleep," was the order. And again Herr Schwartzmann conducted Mademoiselle Delacouer to her cabin, while Chet Bullard watched until he saw the man depart and heard the click of the lock on the door of Diane's room.