Irma gave him a skeptical look and he knew his little seminar was boring them again. When he paused, she said, “Why’s this so big? And why’s nobody here?”

Terry said, “You mean, why so much open land?”

Aybe said, “They don’t like cities, maybe? We haven’t seen anything more than towns.”

Cliff nodded. “Even from SunSeeker we didn’t see big metro areas.”

“Maybe the Bird Folk like countryside, not cities,” Irma said. “I know I do.”

They came around a long curve and suddenly the rain died. Without prompting, they all stood and surveyed as far as they could. Terry called, “It’s there!”

The balloon creature was a distant tube hanging above a rocky headland. Cliff hadn’t thought till now that the balloon was subject to the winds that brought the storm. It was plain bad luck that the wind moved the creature to block their path.

Looking through his binocs, Terry called, “They just dispatched one of those silent planes. It’s turning back toward us.”

Only then did Cliff glance in the opposite direction and see that the spire lay behind them. “Damn!” he said. “We have to go back where we were.” So much for running away.

Aybe expertly turned the magcar and took them away, using the canyon walls to keep them screened from the airplane’s view. They ran hard for the spire canyons, which were deeper and afforded more shelter. They all sat in silence. Being hunted was now a gray fear they all carried at the back of their minds, with no letup.

Aybe slowed a bit and let out a yelp. “I got it! I’ve been wondering about that spire. Cliff, check me. We saw a pattern of them from SunSeeker, right?”

“Uh, yeah.”

“I know why. They’re in a grid because they’re part of the construction. They’re stress juncture points!”

They looked at him blankly. “They’re like counterweights, see?” Aybe took his hands off the yoke and gestured, palms perpendicular to each other. “They draw support cables and pair them off against each other in bridges, see?”

Irma said vaguely, “This spinning bowl, it’s like a bridge?”

“Yes,” Aybe said eagerly, “one with both ends tied to each other.”

“Why’s it a spire?” Terry asked.

“I’ll bet there’s a counter-spire on the outside of the bowl, too. It’s all about matching stress.” To their hesitant looks, he added, “Think of it as like an arch, each side supporting the other.”

“An arch works against gravity—,” Terry began.

“And this place works against the centrifugal force—which we feel as gravity,” Aybe said triumphantly.

Cliff liked Aybe’s getting them out of their funk, but had to ask, “So what? I mean, that’s cute but—”

“Don’t you see?” Aybe asked, wide eyed. “The natural place to lay out a transit system is along the stress lines. That’s where the heavy mechanics gets resolved. Plenty of support for rail lines, things like that.”

Cliff thought he got it, but—“So some transport stops here? Like a train station?”

“Or elevator,” Aybe said. “Same thing, really, in a damn weird contraption like this.”

Cliff called up some pictures he had from the SunSeeker surveys. Under high resolution, he could make out the tiny needle points jutting off the back side, pointing at the stars. They formed a grid around the hemisphere and had seemed unimportant at the time. He had been overwhelmed with the whole idea then, just getting his head around it.

“So?” Terry asked. “We’ve got airplanes looking for us—”

“And we can hide, but who knows what kinds of detectors they have?” Aybe rushed on. “So we have to go to ground, get out of their view—”

“Into that subway system you think correlates with the spire, right?” Irma said brightly.

Aybe jerked a thumb up. “Yep! You’re right, it’s more like a subway, buried below us.”

“And where is it?” Cliff said soberly.

“At the spire, of course. Makes engineering sense. I was stupid not to see it before.”

They were all standing and Cliff slapped him on the shoulder. “Great! Sniff it out, then.”

Irma hugged Aybe, and Terry shook his hand, but as he did so, they heard a distant whispering burr. Terry jerked his head. “The plane. It’s coming.”

“We’d better find this subway pretty damn soon,” Cliff said.

They set off, moving fast.

PART VIII

ONE MAN’S MAGIC

One man’s “magic” is another man’s engineering.

—R OBERT A. H EINLEIN

FORTY-ONE

This alien technology had a strange effect on him. Cliff looked at it with foreboding as they approached.

The towering sides of great obsidian-dark slabs let intricate designs play out in the elongated perspectives. Bladelike sheaths of a gleaming yellow metal soared up the flat faces, ornamenting it with geometric shapes that tricked the eye into confusions of perspective. Or Cliff’s eyes, anyway. Triple vertical vents like shark gills suggested a cooling channel.

It loomed above them as they dismounted from the magcar. In the last few hours, they had chased down innumerable narrow canyons, looking for Aybe’s “train station” somewhere near the base of the stony spire. After several false leads into literal blind alleys, their nerves got frayed. Coming back out of a canyon they knew would serve as a perfect trap for their pursuers above, they wondered what waited in the sky. Airplanes swam like sharks in the pale blue and seemed to frighten big flocks of birds into flapping anxiously away. Aybe hugged the magcar to the stone walls, moving into the open only when they were low on the horizon.

Then the magcar nearly ground to a halt, strumming and grinding in its bowels. Aybe had a hard time getting it to inch forward. After a tense while, it surged again. Following a winding gorge that slowly widened, they came upon what Cliff now realized should have been obvious—a broad, steep canyon of what seemed to be a conglomerate blending into green sandstone, water cut and layered. This canyon spread out after a few kilometers into an enormous plaza of rough stone, baking beneath the constant sun. They circled this, still keeping to the walls, until across the expanse they saw a lofty construction sunk into the mass of the rising spire. Cliff judged it to be at least a kilometer high. It took them nearly an hour to circle around to near its base. Then they paused.

Irma said, “Look, tracks.”

Wheeled transport had passed this way many times, leaving a spaghetti snarl of trails. Most were so faint, Cliff had to avert his eyes to see them.

Terry gestured. “Some gouged their way.”

Deep ruts were spaced about ten meters apart. Whatever had come this way stressed the very rock it moved on. The rut rims were rounded, so it must have been long ago. “They go straight into that,” Irma said, pointing to the open entrance at the center of the black façade.

They all hesitated. Aybe moved the magcar forward but again it slowed, muttered and snarled, and slowed even more.

“I hope it’s not failing,” Irma said.

“I can’t figure what’s up.” Aybe shrugged. “Tried the registers in these funny displays, popped open what I could. Most of it’s sealed tight, or has key slots I don’t have tools for. Not like I have the operating manual.”

“We’ve been driving it pretty hard now—” Terry glanced at his right, which meant he consulted his interior software. “—thirteen days. Maybe it needs an oil and lube.”

Irma sniffed. “Smells like a lubricant coming to a boil.”

Cliff let them talk it out, knowing there wasn’t any real choice. He turned his e-gear toward the sun. Once inside, he suspected there would be no chance to get a recharge.

“It makes sense,” Irma was saying. “And we’re at the entrance of this place, so—”

“So we hide the car and see what’s inside,” Cliff said quietly. “Beat it if we find trouble.”