Nelson uttered an exclamation. He had turned to look back, and now he pointed downward. By the glaring light, they could see Nick Sloan's rafts coming down the blood-red river past the blazing city.
"They'll be up here soon," he said edgedly. "Nsharra, there's still time for you to get away!"
"I will show you the safe way into the Cavern, now," she answered. "But I am its Guardian and I will not leave it!"
He turned with her toward that great mouth of cold, quivering light. Deliberately, Nsharra led the way into it.
Just inside the entrance she paused. Nelson looked about. Where the light outside had been red and hot, here it was a cool glow like uncanny moonlight.
The cavity was huge and circular, running back into the hill. Nelson guessed it to be eighty feet high. A hundred feet from where they stood yawned a deep cleft that ran across the cavern floor, and it was from here that the cold light came — a terrific blaze of white radiation flung upward out of the cleft.
Nelson began to see things that astounded him even more than his first sight of Vruun and Anshan.
Great circular ribs of metal, massive girders dim in the lofty gloom, seemed to support the roof and sides of the Cavern. He made out the shapes of metal tubes, gigantic things, crumpled and twisted as though by blasting force, that ran along the walls into the unguessable shadowy spaces farther in.
His brain began to reel with impossible conjectures. Stepping forward toward the cleft, he glimpsed a glowing white mass that lay deep down at the bottom of the crevice.
Nsharra drew him back. "Do not go too close to the cold fire — its light can blast and kill!"