have the whole Solar System for his toy.
There were no more protests. Falken set the ship down with infinite skill on a ledge on the night side. Then he turned, feeling the blood beat in his wrists and throat.
"Vac suits," he said. "There are two and a spare."
They got into them, shuffled through the airlock, and stood still, the first humans on an undiscovered world.
* * * * *
Lead weights in their boots held them so that they could walk. Falken thrust at the rock with a steel-shod alpenstock.
"It's like glass," he said. "Some unfamiliar compound, probably, fused out of raw force in the Solar disturbance that created the planets. That would explain its resistance to heat."
Radio headphones carried Avery's voice back to him clearly, and Falken realized that the stuff of the planet insulated against Solar waves, which would normally have blanketed communication.
"Whatever it is," said Avery, "it sucks up light. That's why it's never been seen. Only little glimmers seep through, too feeble for telescopes even on Mercury to pick up against the Sun. Its mass is too tiny for its transits to be visible, and it doesn't reflect."
"A sort of dark stranger, hiding in space," said Sheila, and shivered. "Look, Eric! Isn't that a cave mouth?"
Falken's heart gave a great leap of hope. There were caves on Pluto. Perhaps, in the hidden heart of this queer world....
They went toward the opening. It was surprisingly warm. Falken guessed that the black rock diffused the Sun's heat instead of stopping it.
Thin ragged spires reared overhead, stabbing at the stars. Furtive glints of light came and went in ebon depths. The cave opened before them, and their torches showed glistening walls dropping sheer away into blackness.
Falken uncoiled a thousand-foot length of synthetic fiber rope from his belt. It was no larger than a spider web, and strong enough to hold Falken and Avery together. He tied it to each of their metal boots to and let it down.
It floated endlessly out, the lead weight dropping slowly in the light gravity. Eight hundred, nine hundred feet. When there were five feet of rope left in Falken's hand it stopped.
"Well," he said. "There is a bottom."
Paul Avery caught his arm. "You aren't going down?"
"Why not?" Falken scowled at him, puzzled. "Stay here, if you prefer. Sheila?"
"I'm coming with you."
"All right," whispered Avery. "I'll come." His amber eyes were momentarily those of a lion caught in a pit. Afraid, and dangerous.
Dangerous? Falken shook his head irritably. He drove his alpenstock into a crack and made the rope fast.
"Hang onto it," he said. "We'll float like balloons, but be careful. I'll go first. If there's anything wrong down there, chuck off your other boot and climb up fast."
They went down, floating endlessly on the weighted rope. Little glints of light fled through the night-dark walls. It grew hot. Then Falken struck a jog in the cleft wall and felt himself sliding down a forty-five-degree offset. Abruptly, there was light.
Falken yelled, in sharp, wild warning.
The thing was almost on him. A colossus with burning eyes set on foot-long stalks, with fanged jaws agape and muscles straining.
Falken grabbed for his blaster. The quick motion overbalanced him. Sheila slid down on him and they fell slowly together, staring helplessly at destruction, charging at them through a rainbow swirl of light.
The creature rushed by, in utter silence.
Paul Avery landed, his blaster ready. Falken and Sheila scrambled up, cold with the sweat of terror.
"What was it?" gasped Sheila.
Falken said shakily, "God knows!" He turned to look at their surroundings.
And swept the others back into the shadow of the cleft.
Riders hunted the colossus. Riders of a shape so mad that even in madness no human could have conceived them. Riders on steeds like the arrowing tails of comets, hallooing on behind a pack of nightmare hounds....
Cold sweat drenched him. "How can they live without air?" he whispered. "And why didn't they see us?"
There was no answer. But they were safe, for the moment. The light, a shifting web of prismatic colors, showed nothing moving.
They stood on a floor of the glassy black rock. Above and on both sides walls curved away into the wild light—sunlight, apparently, splintered by the shell of the planet. Ahead there was a ebon plain, curving to match the curve of the vault.
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