Falken stared at it bitterly. There was no haven here. No life as he knew it could survive in this pit. Yet there was life, of some mad sort. Another time, they might not escape. "Better go back," he said wearily, and turned to catch the rope. The cleft was gone. Smooth and unbroken, the black wall mocked him. Yet he hadn't moved more than two paces. He smothered a swift stab of fear. "Look for it," he snapped. "It must be here." But it wasn't. They searched, and came again together, to stare at each other with eyes already a little mad. Paul Avery laughed sharply. "There's something here," he said. "Something alive." Falken snarled, "Of course, you fool! Those creatures...." "No. Something else. Something laughing at us." "Shut up, Avery," said Sheila. "We can't go to pieces now." "And we can't just stand here glaring." Falken looked out through the rainbow dazzle. "We may as well explore. Perhaps there's another way out." Avery chuckled, without mirth. "And perhaps there isn't. Perhaps there was never a way in. What happened to it, Falken?" "Control yourself," said Falken silkily, "or I'll rip off your oxygen valve. All right. Let's go." They went a long way across the plain in the airless, unechoing silence, slipping on glassy rock, dazzled by the wheeling colors. Then Falken saw the castle. It loomed quite suddenly--a bulk of squat wings with queer, twisted turrets and straggling windows. Falken scowled. He was sure he hadn't seen it before. Perhaps the light.... They hesitated. Icy moth-wings flittered over Falken's skin. He would have gone around, but black walls seemed to stretch endlessly on either side of the castle. "We go in," he said, and shuddered at the thought of meeting folk like those who hunted the flaming-eyed colossus. Blasters ready, they went up flat titanic steps. A hall without doors stretched before them. They went down it. * * * * * Falken had a dizzy sense of _change_. The walls quivered as though with a wash of water over them. And then there were doors opening out of a round hall. He opened one. There was a round hall beyond, with further doors. He turned back. The hall down which they had come had vanished. There were only doors. Hundreds of them, of odd shapes and sizes, like things imperfectly remembered. Paul Avery began to laugh. Falken struck him, hard, over the helmet. He stopped, and Sheila caught Falken's arm, pointing. Shadows came, rushing and wheeling like monstrous birds. Cold dread caught Falken's heart. Shadows, hunting them.... He choked down the mad laughter rising in his own throat. He opened another door. Halls, with doors. The shadows swept after them. Falken hurled the doors open, faster and faster, but there was never anything beyond but another hall, with doors.