Twisted, tumbled, torn and shattered rocks met his eye. Mosses, lichens, a few tough, low-growing plants. It looked like a picture of hell, but it was a prospector's paradise, for the rocks of Io were shot through with veins of gold, silver, platinum, iridium, not to mention the more common iron and copper, which were not sought for because transportation back to earth was too expensive to pay profits. "Off to the right," Oscar whispered. The glint of Jove-glow on a polished sight up the ravine gave Andy an aiming point and he snapped the blaster in that direction. He over-estimated the weak gravity of Io and the pellet hit on top of a high ridge beyond. A most satisfactory explosion took place there. Rocks split and tumbled in every direction. Andy lowered his sights and blasted again. Another brilliant explosion illuminated the landscape, far to the left this time. "You shoot like a rocket-man," Oscar commented. "Shut up," Andy growled. The men who tended the rockets lived in atmosphere of constant hammering from the explosion of the driving charges. A few years handling rockets and a man was unable to hold his hands still, so that old rocket-men always looked like they had well-developed cases of _paralysis agitans_. To tell a navigator, who had to have sure nerves and steady hands, that he resembled a rocket-man was a supreme insult. "Duck, Boss, he's drawing a bead on you," came Oscar's hurried whisper, and Andy jerked his head down behind the boulder just in time to avoid a ray that frothed across the top of the stone. No warning shot, that one. The unknown marksman had fired that shot with honest intentions of doing damage. * * * * * The ray skipped back and forth across the boulder, went over the top and burned into the bluff beyond. Andy watched it, and wondered what in hell all the shooting was about. Io, by order of the Interplanetary Council, was free territory, with the exception of commercial developments, but any straggler was always welcome there, for the sake of his companionship. Andy did not know whether he had stumbled into a space-pirate's lair, or whether some cracked prospector was using him for a target. The ray played out, vanished, but Andy kept his head down and waited. Minutes passed. Gravel crunched at his left and he swung the blaster up, but it was the honey-bear. "Oh, it's you," Andy said. "Get back up there and keep your eye peeled for the man with the ray gun." "He has beat it. I saw him slip back up the ravine and over the ridge." "The deuce he has!" "Yeh. Let's get out of here. This shooting makes me nervous." Andy stuck his head over the boulder. Nothing happened. He waved his cap, sure that this would draw fire, but it didn't. He lifted his blaster, whereupon Oscar hurried out of sight. He loosed a couple of pellets, which tore up great holes in the rocky ravine. There was no answer. He climbed up on the boulder. Only desolation met his eye.