Among the stars it turned southward toward that deepest enigma of Io. Toward the unknown scientific wisdom, which lay hidden somewhere near the Ionian equator. "He'll get there in a few minutes' time," Paul whispered. "And I guess we won't get there at all. I'm sorry, Evan, that I got you mixed up with the Forbidden Moon. Me--I'm just about finished--now." * * * * * Paul Arnold's voice trailed away. Harwich turned the boy's glass-covered face up. In the light of monster Jupiter, he could see that it was blank and relaxed. The eyes were closed. In the quiet rays of the giant of planets, the youth looked as though death had already touched him. But there was a little frosty blur on the inside of the crystalline face-plate of his helmet. It showed that he still breathed. Tottering a little himself, Harwich picked the boy up, pack and all. He struggled to put one foot ahead of the other, marching again toward the south, where the space ship was rapidly receding. Had his strength been at normal level, his load, bulky though it was, would have been light in this weak gravity. But Harwich was near the end of his rope, too. And so he moved on through that beautiful shadow-haunted, frigid night, where no man was meant to live. Many times he had to stop and rest. After a short while, the atomic motor of the air compressor separator unit refused to work any more. Harwich tried turning the mechanism by hand. But this was slow, exhausting work. He watched the luminous dial of the cold-proof wrist-watch, strapped on the outside of one of his heavy space gantlets. His mind was getting dimmer. Cold was biting home, savagely. Harwich wanted to see just how much longer he could keep going. It was eight hours now, since Bayley's ship had appeared. Slowly more time crept by. His boots trudged in the desert dust, mechanically. The hands of his watch moved on. One hour more. Another. Why didn't he desert the dead weight of Paul Arnold? But you never deserted somebody who was like a kid brother, did you? The patrol pilot's breath was coming fast and short, now. The last of his air was being used up. It was useless to try to replenish the oxygen flasks with hand power, even though he was suffocating. Harwich tripped in the dust, and fell sprawling. Jupiter, shining down upon him, somehow looked like a fat face, tremendously bloated in size--the face of George Bayley. Harwich cursed, and tried to crawl toward the south. Did he hear a sound through his oxygen helmet--a sound loud enough for the tenuous Ionian atmosphere to transmit? Or was it only the roaring of the unsteady pulses in his ears? He tried to look ahead, but his vision was very dim, now, and the light of Jupiter and his moons was so confusing. The shadows of the rocks and the ruined buildings were so very black.