With dogged persistence Harwich kept yelling futile warnings into his radio. His shouts and curses were unheeded, and no answer was given. He knew what was going to happen in another second. There would be a burst of dazzling white fire all around the rocket of this foolhardy pilot he had tried to save from suicide. Metal would drip and sparkle in the absolute zero of space. In just another instant.... Harwich swung his patrol boat aside, not caring to end his own life. But he kept watching the X911 from the side-ports of his cabin. And now, something quite different from what he had expected was taking place. Suddenly the apparently doomed ship was enveloped in a bluish halo which seemed to emanate from a great helix or spiral of metal that wrapped its hull! Immediately afterward, as the X911 entered definitely into the zone of destruction around Io, great white sparks lanced dazzlingly through the blue halo. It was as though the latter was fighting back those gigantic, unknown forces that had seemed to make the Forbidden Moon forever inviolable. It was as though the halo was keeping the X911, and whoever was flying it, safe! Evan Harwich's slitted eyes widened a little in astonishment and hope. "Dammit!" he grumbled happily. "That idiot's got some kind of new invention that's protecting him! Maybe the Forbidden Moon is going to be reached and explored after all!" A second more that weird conflict of hidden forces continued. Watching it was like watching a race, on which you have staked everything you own. Visibly, that daredevil space ship seemed to slow, as if resisted by a tangible medium. For an agonizing instant of suspense, Harwich saw those wicked sparks brighten in the X911's bluish aura. Then the latter dimmed, flickered, went out! As if angry demons were waiting to pounce, destruction struck--quicker than a lightning bolt. * * * * * If there had been any humor in the situation before, it was gone now utterly! The patrol man's lips dropped apart in sheer awe. The muscles of his massive, freckle-smeared forearms tightened futilely as he longed to help the X911's doomed pilot. In the pit of his stomach there was a sickish feeling. Where that rocket that had dared the inscrutable enigma of the Forbidden Moon had been, there was a sudden, terrific blaze of light. The intolerable incandescence of it seemed to reach out to infinity itself, illuminating even the blackness between the distant stars of space. But it was all as silent as the bouncing of a bubble on velvet. No explosion, however huge, can transmit sound in the emptiness of the void.