Mason stood up and extended a warm hand. "Your courage will not go unnoticed, boy. The thanks of all Earth will go with you into the void." II Gene nodded sleepily as his ship, _New Frontiers_, drove forward through space. The outermost planets were now far behind in the all-surrounding blackness, and a vague doubt was beginning to worry his mind. Suppose the malignant ray did not originate in this system? Science Center had naturally assumed that the radiation came from some uncharted asteroid or rogue world within the system. But if it didn't, then what? Should he return to Earth and report failure? Gene dismissed the thought as soon as it entered his head. Yet, as the great, staring orb that was Pluto slipped away behind him, the doubt grew stronger and made of itself a steady clamor that would not pass unheeded. His ship still followed the swath of the ray; a never-ending, invisible beam that would seem to sprout from the very emptiness of space itself. Mason had warned Gene that he might face untold danger at the ray's source, but the explorer could not see how that danger could come from any living thing. Here in the farthermost reaches of the system, far from the warmth of the sun, what strange organic creature could find sustenance? He stifled a yawn, fighting doggedly to keep his heavy lids from closing in slumber. Sleep was out of the question. He could take no chance of losing the unseen trail of that devilish radiation, so that meant he had to go it without the help of the automatic controls. In spite of Gene's efforts to remain awake, his brown-thatched head slowly lowered against his chest. Tortured eyes no longer registered the monotonous gray of the ship's cabin as leaden lids closed over them. He was asleep. Instants later, the insistent clang of a warning bell penetrated through his torpor, whipping away the blanket of sleep and bringing the drowsing biologist at once to alert wakefulness. He reached out frantically, his fingers flying unerringly over the myriad controls, jabbing viciously at the studs regulating the batteries of rocket tubes. _Something was pulling, tugging, at the small ship, drawing it down, held in a relentless clutch that grew stronger with each passing moment!_ The ship surged with power; steel crossbeams groaned and screeched, threatening to buckle under the strain placed on them. And still it rushed downward! He cursed wildly and punched hard at the stud controlling the forward tubes. The craft lurched drunkenly under this new force, then continued its downward flight, moving not quite so fast now.