met its end, and at the thought of the Invaders the chill of space itself came seeping into their bones.
Then they would turn once more to the life and warmth of the city, to the long golden age whose beginning was already lost and whose end was yet more distant. Other men had dreamed of such an age, but they alone had achieved it.
They had lived in the same city, had walked the same miraculously unchanging streets, while more than a billion years had worn away.
Chapter One
It had taken them many hours to fight their way out of the Cave of the White Worms. Even now, they could not be sure that some of the pallid monsters were not pursuing them -and the power of their weapons was almost exhausted. Ahead, the floating arrow of light that had been their mysterious guide through the labyrinths of the Crystal Mountain still beckoned them on. They had no choice but to follow it, though as it had done so many times before it might lead them into yet more frightful dangers.
Alvin glanced back to see if all his companions were still with him. Alystra was close behind, carrying the sphere of cold but ever-burning light that had revealed such horrors and such beauty since their adventure had begun. The pale white radiance flooded the narrow corridor and splashed from the glittering walls; while its power lasted, they could see where they were going and could detect the presence of any visible dangers. But the greatest dangers in these caves, Alvin knew too well, were not the visible ones at all.
Behind Alystra, struggling with the weight of their projectors, came Narrillian and Floranus. Alvin wondered briefly why tose projectors were so heavy, since it would have been such a simple matter to provide them with gravity neutralizers. He was always thinking of points like this, even in the midst of the most desperate adventures. When such thoughts crossed his mind, it seemed as if the structure of reality trembled for an instant, and that behind the world of the senses he caught a glimpse of another and totally different universe...
The corridor ended in a blank wall. Had the arrow betrayed them again? No-even as they approached, the rock began to crumble into dust. Through the wall pierced a spinning metal spear, which broadened rapidly into a giant screw. Alvin and his friends moved back, waiting for the machine to force its way into the cave. With a deafening screech of metal upon rock-which surely must echo through all the recesses of the Mountain, and waken all its nightmare brood!-the subterrene smashed through the wall and came to rest beside them. A massive door opened, and Callistron appeared, shouting to them to hurry. ("Why Callistron?" wondered Alvin. "Whats he doing here?") A moment later they were in safety, and the machine lurched forward as it began its journey through the depths of the earth.
The adventure was over. Soon, as always happened, they would be home, and all the wonder, the terror, and the excitement would be behind them. They were tired and content.
Alvin could tell from the tilt of the floor that the subterrene was heading down into the earth. Presumably Callistron knew what he was doing, and this was the way that led to home. Yet it seemed a pity...
"Callistron," he said suddenly, "why don't we go upward? No one knows what the Crystal Mountain really looks like. How wonderful it would be to come out somewhere on its slopes, to see the sky and all the land around it. We've been underground long enough."
Even as he said these words, he somehow knew that they were wrong. Alystra gave a strangled scream, the interior of the subterrene wavered like an image seen through water, and behind and beyond the metal walls that surrounded him Alvin once more glimpsed that other universe. The two worlds seemed in conflict, first one and then the other predominating. Then quite suddenly, it was all over. There was a snapping, rending sensation-and the dream had ended. Alvin was back in Diaspar, in his own familiar room, floating a foot or two above the floor as the gravity field protected him from the bruising contact of brute matter.
He was himself again. This was reality-and he knew exactly what would happen next.
Alystra was the first to appear. She was more upset than annoyed, for she was very much in love with Alvin.
"Oh, Alvin!" she lamented as she looked down at