Maybe it was because he'd never seen anything like it before, but the city simply hadn't registered in Hayden's mind until this moment. After all, the towns of Aerie were seldom more than two hundred yards across, and were simply wheels made of wooden planks lashed together and spoked with rope. You spun up the whole assembly and built houses on the inside surface of the wheel. Simple. And never had he seen more than five or six such wheels in one place.

The dozens of towns that made up Rush gleamed of highly polished metal. They were more cylindrical than ring-shaped, and none was less than five hundred yards in diameter. The most amazing tiling was that they were tethered to the forested asteroid in quartets like mobiles; radiating from each cylinder's outer rim were bright sails of gold and red that transformed them from there towns into gorgeous pinwheels.

"The asteroid's too big to be affected by the wind," said Father. Hayden shifted uncomfortably; Father was not trying to hide the burr of his provincial Aerie accent. "The towns are small enough to get pulled around by gusts. They use the sails to help keep the wheels spun up." This made sense to Hayden, because wind was the result of your moving at a different speed than whatever airmass you were in. Most of the time, objects migrated outward and inward in Virga to the rhythm of slowly circulating rivers of air. You normally only experienced wind at the walls of a town or while flying. Many times, he had folded little propellers of paper and let them out on strings. They'd twirled in the rushing air. So did the towns of Rush, only much more slowly.

Hayden frowned. "If that big rock isn't moving with the air, won't it drift away from the rest of Slipstream?"

"You've hit on the very problem," said Father with a smile. "Slipstream's more migratory than most countries. The Slipstreamers have to follow their asteroid's orbit within Virga. You can't see from here, but their sun is also tethered to the asteroid. Ten years ago, Slipstream drifted right into Aerie. Before that, we were a smaller and less wealthy nation, being far from the major suns. But we were proud. We controlled our own destiny. Now what are we? Nothing but vassals of Rush."

Hayden barely heard him. He was eagerly staring at the city.

Their ship arrived at midday to find a traffic jam at the axis of one of the biggest cylinders. It took an hour to disembark, but Hayden didn't care. He spent the time watching the heavily built-up inner surface of the town revolve past. He was looking for places to visit. From the axis of the cylinder, where the docks sat like a jumble of big wooden dice, cable-ways radiated away to the other towns that made up the city. One wheel in particular caught his eye—a huge cylinder whose inside seemed to be one single building with balconies, coigns and glittering glass-paneled windows festooning it. This cylinder was surrounded by warships, which Hayden had seen in photos but never been close to before. The massive wooden vessels bristled with gun ports, and they trailed smoke and ropes and masts like the spines of fish. They were majestic and fascinating.

"You'll never get there," said Father dryly. "That's the pilot's palace."

After ages they were finally able to descend the long, curving, covered stairway to the street. Here Hayden had to endure another interminable wait while a man in a uniform examined Father's papers. Hayden was too distracted at the time to really notice his father's falsely jovial manner, or the way his shoulders had slumped with relief when they were finally accepted into the city. But after some walking he turned to Mother and kissed her, saying quietly, "I'll be back soon. Check us into the hotel, but don't wait for me. Go and do some shopping, it'll take your mind off it."

"Where's he going?" Hayden watched as Father disappeared into the crowd.

"It's just business," she said, but she sounded unhappy.

Hayden quickly forgot any misgivings this exchange might have raised. The town was huge and fascinating. Even the gravity felt different—a slower turnover of the inner ear—and there were points where you couldn't see the edges of the place at all. He followed his mother around to various outlets and while she haggled over wholesale paper prices for the newspaper she helped run, Hayden was happy to stare out the shop's windows at the passing crowds.

Gradually, though, he did begin to notice something. Mother was dressed in the layered and colorful garments of the Aerie outer districts and, like Father, made no attempt to hide her accent. Even her black hair and dark eyes marked her as different here in this city of fair-haired, pale-eyed people. Though the shopkeepers weren't actually hostile to Mother, they weren't being very friendly either. Neither were the other kids he saw in the street. Hayden smiled at one or two, but they just turned away.

He could have forgotten these details if not for what happened next. As they approached the hotel late that afternoon—Hayden laden with packages, his mother humming happily—he spotted Father at the hotel entrance, standing with his hands behind his back. Hayden felt his mother clutch his shoulder even as he waved and shouted a hello. It was only then that he noticed the men standing with his father, men in uniform who turned as one at the sound of Hayden's voice.

"Shit," whispered Mother as the policemen converged on her and a very confused Hayden.

The rest of the trip mostly consisted of waiting in various pale-green, bare rooms with his mother, who sat white-faced and silent, not answering any of Hayden's increasingly petulant questions. They didn't go back to the hotel to sleep, but were given a couple of rough cots in a small room in the back of the police station. "Not a cell," said the sergeant who showed them to it. "A courtesy apartment for relatives."

Father had reappeared the next day. He was disheveled, subdued, and had a bruise on his cheek. Mother wept in his arms while Hayden stood nearby, hugging his own chest in confused anger. Later that day they boarded a passenger ship considerably less posh than the one they had arrived on, and Hayden watched the bright pin-wheels of Rush recede in the distance, unexplored.

Later Father had explained about the Resistance and the importance of assembling the talent and resources Aerie needed to strike out on its own. Hayden thought he understood, but what mattered was not the politics of it; it was the memory of walking through Rush's crowded streets next to his father, whose hands were bound behind his back.

THE GALLERY WAS just a stretch of street empty of fence, but with a railing you could look over. Mother called it a "braveway"; Miles used the more interesting term "pukesight." Hayden stepped up to the rail and clutched it with both hands, staring.

A gigantic mountain of cloud wheeled in front of him, nearly close enough to touch. The new sun must be behind it; the ropes of the road from Gavin Town to the construction site stabbed the heart of the cloud and vanished inside it. Hayden was disappointed; if the sun came on right now he wouldn't see it.

He laughed. Oh, yes he would. Father had impressed it upon him again and again: when the sun came on, there would be no missing it. "The clouds for miles around will evaporate—poof," he'd said with a wave of his fingers. "The temperature will instantly shoot up, in fact everything within a kilometer is going to catch fire. That's why the sun is situated so far from any towns. That, and security reasons, of course. And the light… Hayden, you have to promise not to look at it. It's going to be brighter than anything you can imagine. Up close, it could burn your skin and dazzle you through your closed eyelids. Never look directly at it, not until we've moved the town."

The cloud appeared to rotate as Hayden gazed at it; Gavin Town was a wheel like all towns, after all, and spun to provide its inhabitants with centrifugal gravity. It was the only form of gravity they would ever know, and it was a precious resource, costly and heavily taxed. Grant's Chance, the next nearest town, lay a dozen miles beyond the sun site, invisible for now behind cloud.