Far above, in the main saloon, the regular evening dance was in full swing. The ship's orchestra crashed into silence, there was a patter of applause and Clio Marsden, radiant belle of the voyage, led her partner out into the promenade and up to one of the observation plates. "Oh, we can't see the earth any more!" she exclaimed. "Which way do you turn this, Mr. Costigan?" "Like this," and Conway Costigan, burly young first officer of the liner, turned the dials. "There--this plate is looking back, or down, at Tellus; this other one is looking ahead." Earth was a brilliantly shining crescent far beneath the flying vessel. Above her, ruddy Mars and silvery Jupiter blazed in splendor ineffable against a background of utterly indescribable blackness--a background thickly besprinkled with dimensionless points of dazzling brilliance which were the stars. "Oh, isn't it wonderful!" breathed the girl, awed. "Of course, I suppose that it's old stuff to you, but I--a ground-gripper, you know, and I could look at it forever, I think. That's why I want to come out here after every dance. You know, I ..." Her voice broke off suddenly, with a queer, rasping catch, as she seized his arm in a frantic clutch and as quickly went limp. He stared at her sharply, and understood instantly the message written in her eyes--eyes now enlarged, staring hard, brilliant, and full of soul-searing terror as she slumped down, helpless but for his support. In the act of exhaling as he was, lungs almost entirely empty, yet he held his breath until he had seized the microphone from his belt and had snapped the lever to "emergency." "Control room!" he gasped then, and every speaker throughout the great cruiser of the void blared out the warning as he forced his already evacuated lungs to absolute emptiness. "Vee-Two Gas! Get tight!" Writhing and twisting in his fierce struggle to keep his lungs from gulping in a draft of that noxious atmosphere, and with the unconscious form of the girl draped limply over his left arm, Costigan leaped toward the portal of the nearest lifeboat. Orchestra instruments crashed to the floor and dancing couples fell and sprawled inertly while the tortured First Officer swung the door of the lifeboat open and dashed across the tiny room to the air-valves. Throwing them wide open, he put his mouth to the orifice and let his laboring lungs gasp their eager fill of the cold blast roaring from the tanks. Then, air-hunger partially assuaged, he again held his breath, broke open the emergency locker, donned one of the space-suits always kept there, and opened its valves wide in order to flush out of his uniform any lingering trace of the lethal gas.