"Lana, it looks like we're in for it," he said grimly. "That's high pressure you feel. Pretty soon your ears will begin to ring. And if we don't hurry we may never get back to boast about things here to our sappy friends at home." When the heavy pressure areas came over Uranus, mists rose high in the air and dispersed slowly. Swift expansion of atmospheric gases caused a tremendous surface pressure that would last for some time. It meant a quick crushing death under air compression if they didn't reach the mud-submarine. Lana Hilton was white with fright and trying hard not to show it. A strange metamorphosis was taking place in the heavens. Lancing colors of orange and red shot up like gigantic swords to flash across the sky. His ears began to throb dully. As the mist rose Lonny saw that they had come too far to the left and that the mud-ship was a hundred yards directly to their right. He saw something else, too. A man was running across the muddy surface--if his fast wobbling progress on mud-shoes could have been described as a run. It could be only one person--Link Raeburn. A terrible fear seized him. If Raeburn reached the mud-ship and shut them out, they would die horribly. He began to hurry forward--slipped and fell awkwardly. Lana made a wry face and helped him to his feet. "The rat," she gasped. "He heard you refer to my bag of pearls as a mere 'handful'. It wouldn't do you any harm to think once in a while before speaking, big boy." Handful--of course her small collection was a handful compared to his own rich pickings. So that was why she had come with him! The world was going around in a whirl now, but Lonny kept staggering onward. Link Raeburn had disappeared. The mud-submarine kept dancing tauntingly before his eyes and then disappearing. If it sank before he reached it the work of long endless months would slip from his grasp. And with it would go his life. Back on earth, they would never know and Raeburn would live a life of affluence and ease. "We've got to make it, Lana," he gritted, though every breath was a torment that sent hot flames of pain shooting through every cell. She turned a game, tortured face to his and nodded vehemently. A whole school of whirl-rays came rippling toward them, crisscrossing the mud with gleaming trails, and Lonny found his Z-ray weapon--sent the purplish beams of annihilation down into the centers of quivering, living whirlpools. Once he went around and around in narrowing circles toward the opened maw of a whirl-ray, only to see the lower shape dematerialize before the deadly emanation. * * * * * They were at the very edge of the submarine, were clambering across the muddy landing, using their last reserve of strength. Link Raeburn was working at the catches of the hatch cover, and had just succeeded in undoing the fastenings. Now he gave a tremendous heave and the thing fell like a trapdoor.