The thought of demure Clara Arnold in the arms of that bulky, squint-eyed printer, who had shown his true colors at last, and proved his diabolical cleverness, fairly strangled Harwich. Maybe he had no right to harbor such an attitude. After all he hardly knew Clara. He only knew her haunting beauty and friendly amber eyes, with quiet wisdom and a little of the martyr in them--like her father, perhaps. But Harwich couldn't help thinking. It was only by exercising super-human self-control, that he kept himself from turning into a raving maniac. Supporting Paul Arnold's feeble, struggling steps, Harwich watched the sky like a starved, wounded wolf. Sometimes, in sheer, wild determination, he longed to claw at that cold, forbidding firmament, and climb out of that hell-pit of a world into which he had fallen. He yearned with a savagery beyond words to claw his way up there into space, to wherever George Bayley might be, and feel the fat throat of the man who had tampered with the Gyon condenser aboard the RQ257, squeezed between his hooked fingers. But the frigid sky and the bleak, dying hills, and the weary miles, mocked all his hate-born desires. His numbed, aching feet could only plod on and on in this grave-like desert. Ruins, rusted machinery, silence, and cold that crept even through the heavy insulation of his space armor. Still, he could remember another thing. In the far distance to the south, was something wonderful and strange. Something that made the deadly and insidious energy barrier of the Forbidden Moon possible. Where the Tower loomed on the astronomical photographs of Io. That night came at last when a streak of silver fire traced its way across the sky. It couldn't be anything but the flames ejected from the rockets of an approaching space ship. Paul Arnold saw it too, turning his haggard face upward. "There he is, Evan," he croaked into his helmet phones. "Bayley's coming at last." "I see," Harwich returned softly; his teeth gritted and his lips curling furiously, behind the transparent front of his space headgear. They dropped down beside the wall of a ruin, to watch. The ship was coming straight in, toward Io. At its tremendous altitude, nothing but its rocket blasts could be seen at first. But then there was a sudden flare of bluish light. It had struck Io's force barrier, and that blue glow was the evidence of a Penetrator, functioning. The craft seemed to slow a little, as its pale, protecting shell of counter-energy fought back that invisible, guardian screen of the devil moon. "He got through the force shield," Harwich growled after a moment. "We knew he would, of course, with his Penetrator operating right. Damn him!" There was no more blue fire visible now; but the little silver-tailed path of rocket flame, showed that the ship was coming in safe and sound, its propelling jets working steadily.