The cold stream of thought had stopped and another thought broke in, a little piping thought. Perhaps, thought Gary, one of the little slug-like creatures in the glass cage.

Disgusting little things!

Gary looked at the mottled, droopy-eyed creature that squatted opposite him. It raised its head and in the beady eyes he imagined that he caught a glimmer of amusement.

"By the Lord," he said to himself, "he thinks it's funny, too."

This arguing of hideous entities! The piping thoughts of slimy things that should be wriggling through some stagnant roadside ditch back on the planet Earth. The cold thought of the brain-blasting thing that lived on a planet covered by miles of swirling gases. The pinpoint eyes of the being with the mottled skin.

Cosmic Crusade! He laughed to himself, deep in his throat. This wasn't the way he had imagined it. He had thought of gleaming ships of war, of stabbing rays, of might arrayed against might, a place where courage would be at a premium.

But there was nothing to fight. No physical thing. Nothing a man could get at. Another universe, a mighty thing of curving space and time… that was the enemy. A man simply couldn't do anything about a thing like that.

"This place," Herb whispered to him, "is giving me the creeps."

CHAPTER Nine

"WE CAN do it," said Caroline. She flicked a pencil against a sheet of calculations. "This proves it," she declared.

Kingsley bent over her shoulder to look at the sheet. "If you don't mind," he said, "would you lead me through it all again. Go slowly, please. I find it hard to grasp a lot of it."

"Kingsley," said Herb, "you're just an amateur. To get as good as she is you'd have to think for forty lifetimes."

"You embarrass me," she said. "It's very simple. It's really very simple."

"I'll say it's simple," said Tommy. "Just a little matter of bending space and time into a tiny universe. Wrapping it about a selected bit of matter and making it stay put."

"You could use it to control the energy," rumbled Kingsley. "I understand that well enough. When the universes begin to rub you could trap the incoming energy in an artificial universe. The energy would destroy that universe, but you'd have another ready for it. What I can't understand is how you form this artificial fourth-dimensional space."

"It isn't artificial," snapped Gary. "It's real… as real as the universe we live in. But it's made by human beings instead of by some law we have no inkling of."

He pointed at the sheet of calculations. "Perhaps the secret of all the universe is on that sheet of paper," he declared. "Maybe that's the key to how the universe was formed."

"Maybe," rumbled Kingsley, "and maybe not. There may be many ways to do it."

"One," said Gary, "is good enough for me."

"There's just one thing," said Caroline, "that bothers me. We don't know anything about the fifth-dimensional inter-space. We can imagine that its laws are different from our own. Vastly different. But how do they differ? What kind of energy would be formed out there? What form would it take?" She looked from one to the other of them. "That would make a lot of difference," she declared.

"It would," agreed Kingsley. "It would make a lot of difference. It would be like setting a trap for some animal. You might set one for a rat and catch a bear… or the other way around."

"The Hellhounds know," said Tommy. "They know how to navigate in the inter-space."

"But they wouldn't tell us," said Gary. "They don't want the universe to be saved. They want it to be wrecked so they can build a new world out of the wreckage."

"It might be light, or matter, or heat, or motion, or it might be something that's entirely different," said Caroline. "It's not impossible it would be something else, some new fearful form of energy with which we are entirely unacquainted. Conditions would be just as different out in inter-space as fourth-dimensional conditions differ from our three-dimensional world."

"And to be able to control it we would have to have some idea as to what it is," said Kingsley.

"Or what it would become when it entered the hyperspace," said Gary. "It might be one kind of energy out there, an entirely different kind when it entered our universe."

"The people of the other universe don't seem to know," Tommy pointed out. "Even if they are the ones who found out about the universes drifting together. They don't seem to be able to find out too much about it."

Gary glanced around the laboratory, a mighty vaulted room that glowed with soft, white light… a room with gleaming tiers of apparatus, with mighty machines, great engines purring with tremendous power, uncanny structures that almost defied description.

"The funniest thing about the whole business," he declared, "is why the Engineers themselves can't make any progress. Why do they have to call us in? With all of this equipment, with the knowledge they already hold, it ought to be a cinch for them to do almost anything.".

"There's something queer here," Herb declared. "I've been snooping around a bit and this city is enough to set you batty. There isn't any traffic in the streets. You can travel for hours and you don't see a single Engineer. No business houses, no theaters, no nothing. All the buildings are empty. Just empty buildings. A city of empty buildings." He puffed out his breath. "Like a city that was built and waiting for someone. Waiting for someone who never came."

Something akin to terror crossed Gary's mind. A queer, haunted feeling… a pity for those magnificent white buildings standing all untenanted.

"A city built for billions of people," said Herb. "And no one in it. Just a handful of Engineers. Probably not more than a hundred thousand altogether."

Kingsley was clenching and opening his fists again, rumbling in his throat.

"It does seem queer," he said, "that they never found the answer. With all their knowledge, all their scientific apparatus."

Gary looked at Caroline and smiled. A wisp of a girl. But one who could bend space and time until it formed a sphere… or, rather, a hypersphere. A girl who could mold space as she wanted it, who could play tricks with it, make it do what she wanted it to do. She could set up a tiny replica of the universe, a little private universe that belonged to her and no one else. No one before, he was certain, ever had dared to think of doing that.

He looked at her again, a swift, sure look that saw the square-cut chin, the high forehead, the braided raven strands about her head. Was Caroline Martin greater than the Engineers? Could she master a problem that they couldn't even touch? Was she, all unheralded, the master mind of the entire universe? Did the hope of the universe lie within her mind?

It seemed impossible. And yet, she had thought of time and space for nearly forty lifetimes. With nothing but a brain to work with, with no tools, no chance of experimentation — all alone, with nothing but her thoughts, she had solved the deep-shrouded mysteries of space and time. Never dreaming, perhaps, that such knowledge could be used to a certain purpose.

Metal feet scraped across the laboratory floor and Gary whirled to come face to face with Engineer 1824. The metal man had advanced upon them unawares.

His thought came to them, clear, calm, unhurried thought, devoid of all emotion, impersonal, yet with a touch of almost human warmth.

"I heard your thoughts," he said, "and I am afraid that you might think I meant to hear them. But I am very glad I did. You wonder why the Engineers brought you here. You wonder why the Engineers can't do this work unaided."

They stood guiltily, like schoolboys caught at some forbidden act.

"I will tell you," the thought went on, "and I hope you will understand. It is difficult to tell you. Hard to tell you, because we Engineers are full of pride. Conditions being different, we would never tell you."