Luz stared at the sky, gray and cloudless as ever in the spring heat.

"That is a bruised sky," he said, punctuating his words with his hand. "That is a torn-up sky."

His mood suddenly changed in a way that made Luz think of a deflating tire. He leaned against the corner support pole of the shop. "You don't know what our ancestors did to this world. There's so much less of everything. And if there is one reason for it, it's in what this stranger told you. Forever, hah! It takes as long to get somewhere as it should take - his expedience leads to war and flood."

Luz didn't understand half of what he was saying.

"What about the Federals?" she asked. "They drive trucks and have flying machines."

Papa waved his hand. "We are not the Federals. We live lightly upon the earth, light enough that the wounds they deal it will heal. Your grandparents' generation fought wars so that we could rescue the world from excess. People like us act as stewards; we save the rivers and the sky and the land from the worst that people like them do. When you're older you'll understand."

Luz considered that for a moment, then said, "People like us and people like the Federals?"

Papa looked at her. "Yes, Luz."

"What about people that aren't like either?" Luz asked.

Papa hadn't answered her before Priscilla came tearing down the street. "Luz! They took him! They came and took Fizz and his machine both! Caleb couldn't stop them!"

She slid to a halt next to them in a cloud of dust. "It was Samuel! He brought the deputies!"

Luz instantly hopped on her bike and saw from the corner of her eye that her father was pulling his own out from behind the workbench. She didn't wait for him to catch up.

Hours later, Luz and Caleb pedaled along abandoned streets behind the tannery and the vinegar works, searching for the stockade where the deputies had taken Fizz. They might have missed him if he hadn't shouted to them.

"Hey! Luz!"

Fizz was leaning half out of a ground-floor window in an old brick building set in an unkempt lawn of weeds and trash. As they rode over to him, a deputy rounded the corner and told Fizz to stay inside the window. Clearly, the deputies weren't used to having prisoners. When Caleb asked if they could speak to Fizz, the man shrugged and instructed them not to let him escape.

"The trial's tonight," the deputy said, then went back to the corner, where he sat on a stool and idly turned the letterpressed pages of last week's town newsletter.

"I've had it worse, that's for sure," Fizz told them. "They seem a lot more concerned with Rudolf than they are with me. I hope your father didn't get in trouble for its being at your house."

Luz and Caleb glanced at each other. The car had been much easier to locate than its driver. It had been dragged to the front yard of the courthouse.

"No," said Luz. "Papa's fine."

"I don't think Rudolf will be able to say the same," Caleb said, "when this is over."

Fizz's serious expression made Luz notch her guess of his age up another year or two. But then he flashed a wide grin and said, "Rudolf's never offered an opinion on anything at all, Caleb. We hit the road before I figured out how to make him talk."

When they didn't join his laughter, Fizz said, "I see that you're worried. Don't be. I've been in communities like yours before. Heck, I've even been in jails like this one before. Your council and"- he raised his eyebrow -"I'm guessing your father, too? They're more concerned about the presence of the machine than the machinist. They'll debate and storm and glower about what to do with me and Rudolf for an hour and then send us on our way."

Luz said, "Papa's name came up in the lottery at New Year's, so he is on the council this year. And, yes, he's concerned about the machine and its being here. But I think he's even more concerned about the use you put it to."

Fizz didn't reply. He gazed at her steadily, as if she knew the answer to a question he'd forgotten to ask aloud.

"'Everybody could go everywhere,'" she finally said, quoting him.

"Ah," Fizz said. "Your friend said that everybody still can."

Luz shook her head. "I don't think Samuel is my friend anymore. And anyway," she added, her voice unexpectedly bitter, "he's never wanted to go anywhere."

Fizz was sympathetic. "What about you?" he asked her. "Where would you go if you could?"

Luz thought about it for a moment. She remembered Fizz's description of his route along the Gulf of Mexico, but even more, she remembered her grandmother's stories of California.

"I would go to the ocean," she said. "My grandmother was a surfer. You know, on the waves?" She held her palm out flat and rocked it back and forth.

Fizz nodded.

"She says that I'm built right for it. It sounds . . . fast."

"And light on the earth, too," Fizz said. "That's the saying, right?"

"Close," said Caleb, frowning at them both. "It's 'lightly upon the earth.'"

Luz had never thought about how often she heard the phrase. It was something said in the community over and over again. "How did you know people say that here?" she asked.

Fizz shrugged. "People say it everywhere."

Luz had expected her father and the other council members to be arrayed behind a long table in the courtyard square. She had expected the whole town to turn out to watch the proceedings - and even for Fizz to be marched out by the deputies with his hands tied before him with a coil of rope.

She had not expected Federal marshals.

There were two of them, a silver-haired man and a grim-faced woman. Neither of them bothered to dismount their strange half-machine horses, only issuing terse orders to the closest townspeople to fetch pails of coal, which they then turned into the furnaces atop the hybrid creatures' hindquarters. They seemed impatient, as was ever the way with Federals.

Luz sat on the ground in front of a bench crowded with older people, leaning against her grandmother's knees. "I thought the covenants between the town and the Federals guaranteed us the right to have our own trials," Luz said.

Her abuela patted her shoulder, though there was nothing of rea.s.surance in it. "My son," she said, speaking of Luz's father, "is more afraid of what this Fizz can do to us than what the Federals can. The council asked the marshals here."

Before Luz could express her dismay at this news, the council chair banged on the table with a wrench to quiet the crowd. "We're in extraordinary session, people," she said, "and the only order of business is the forbidden technology this boy from . . . North Carolina has brought to our town."

Before anything more could be said, Luz's father raised his hand to be recognized. "I move we close this meeting," he said. "We'll be talking of things our children shouldn't be made to hear."

The gathered townspeople murmured at this, and Luz was surprised at the tone. She would have expected them to be upset that they couldn't watch the proceedings, but - except for the others her age - most sounded like they were agreeing with her father. Before any of the council members could respond to the suggestion, Fizz spoke up.

"I believe I'm allowed to speak?" he asked. "That's been the way of it with the other town councils."

Luz saw the woman marshal lean over in her saddle and whisper something to her partner, whose dead-eyed gaze never shifted from Fizz.

The chairwoman saw the exchange, too, and seemed troubled by it. "Yes," she told Fizz. "We've heard this isn't the first time you've been brought up on these charges. But you should be careful you don't say anything to incriminate yourself. It might not be us that carries out whatever sentence we decide on."

Fizz looked directly at the marshals and then at the council. "Yes, ma'am," he said. "I see that. I've not been in a town controlled by the Federal government before."

Luz's father's angry interruption cut through the noise from the crowd. "Here, now!" he said. "We're as sovereign as any other town in America and signatory to covenants that reserve justice to ourselves. It's our laws you've flouted and our ruling that will decide your fate. These marshals are here at our invitation because we want to demonstrate how seriously we take your crimes. And to tell us what other crimes you've committed before now."

Luz did not realize she had stood until she spoke. "What crimes?"

Her father frowned at her. "Sit down, Luza," he said.

Before she could respond, Fizz spoke. "I can choose someone of the Locality to speak on my behalf, isn't that right? I choose her. I want Luz to be my advocate."

To Luz's surprise - to everyone's surprise - the voice that answered did not come from the council, but from one of the Federals.

"Oh, for G.o.d's sake," the woman said, directing her words to the woman at the head of the council table. "Salma, we came here to destroy this unauthorized car as a favor to you, not to watch you Luddites play at justice."

The councilwoman answered, "You know our ways, Marshal. We must reach a verdict against this . . . what did you say his name is again?"

Luz expected Fizz to speak up, but to her surprise, the marshal answered. "His name is Humility-Before-the-Lord Bradford. He was a ward of the Localist Shaker chapter at Tobaccoville in North Carolina."

"Was, you say?" the councilwoman asked. "He was expelled?"

The marshal shrugged. "He left. The Shakers don't have as good a retention rate as you do."

For the first time, Fizz appeared confused, even frightened.

The marshal spoke on. "Vehicles like this are against our laws, no matter what your play council decides," she said. "We don't have to wait for any verdict to deal with the evidence." With that, she and her partner whistled high and hard.

The marshals dismounted and the horses leaped.

Their lips curled back, exposing spikes where an unaltered horse's teeth would be. Long claws extended from the dewlaps above their steel-shod hooves, and the muscles rippling beneath their flanks were square and hard. They jumped to opposite sides of the car, steam and smoke belching from their noses and ears as they struck and bit, kicked and tore. The sounds of metal ripping and wood splitting rang across the square, frighteningly loud, yet still not loud enough to drown the cries of the children in the crowd. Luz was as shocked by the sounds the horses made as she was by the savagery of their a.s.sault.

In moments, the car called Rudolf was a pile of sc.r.a.p metal and wood. The horses' spikes and claws retracted as they trotted back to their riders, who waited with more skips of coal to replenish what the horses had burned up in the destruction.

No one spoke. Luz watched Fizz blink, as dazed as when they'd met him.

Finally, the Federals swung into their saddles and the woman turned to the councilwoman once more. "Do you want us to take your prisoner off your hands, too? We're better equipped to deal with his kind than you."

"No!" said Luz.

The attention of the crowd fell on her like a weight. She said, "You've destroyed enough. You . . . get away from here."

The woman and the dead-eyed man exchanged ugly grins, waiting. When no one protested, the marshals put the spurs to their mounts and left the square.

Luz turned to the council. "And you . . . What is all this? Papa, you can't stand the Federals and their ways. None of you can. You'd put us in their debt for something you wouldn't even discuss in front of us?"

Of all the people sitting behind the table, only her father would meet her gaze.

"We protect our children from such concerns until they've reached their majority, Luz," he said. "You know that. But since you all just saw . . . what we all just saw . . ." He hesitated for a moment. "It's what I said earlier, Luz," he continued. "Your friend there has a personal car, and that's the source of so much bad in the world that I can't even begin to explain it to you. It can't be allowed."

Luz rolled her eyes and walked over to the pile of debris that had been Rudolf. She pointed to it and said, "This, you mean? It doesn't look to me like he has a car anymore."

She expected Fizz to agree, but he was still staring at the wreckage. For once, he had nothing to say.

But I'm his advocate, she remembered.

"You should let him go," she said. "We should let him go."

Before her father could respond, the chairwoman called him closer. They exchanged a few murmured words. Then she said, "The young man is no longer a danger to our community, or to the earth. He's free to go. This meeting is at an end."

Luz's father added, "He must go."

The council members rose, and the people in the crowd stood and milled around, everyone talking about what had just happened. Luz spotted her father approaching, and then she saw her abuela shake her head to stop him from coming nearer.

Luz thought about what she had learned from her father about making and repairing things. She thought about what she had learned from her mother about scavenging. She thought of the stories told to her by her grandmother of gliding across an ocean's wave.

Luz went to Fizz. She put her hand on his shoulder, whoever he was. "I know where we can get some parts," she said.

The first time I see her, she's standing alone behind the library, looking at the ground. Faded blue dress, scruffy leather jacket, long lace-up boots, and black-rimmed gla.s.ses. But what really makes me stop and stare is the hat: a weird old leather thing that hangs down over her ears, with big thick goggles strapped to the front.

Turns out she's in my English cla.s.s. She sits right next to me, still wearing the jacket and goggles and hat. She smells like a thrift store.

"Weirdo," says Michael Carmichael.

"Freak," says Amanda Anderson.

She ignores the laughter, reaching into her bag for a notebook and pencil. She bends low so no one can see what she's writing.

Later, when Mrs. Hendricks is dealing with an outbreak of giggles at the front of the cla.s.s, I lean over and whisper, "What's with the hat?"

She glances at me with a tiny frown, then turns back to her notebook. Her eyebrows are the color of cheese.

"Not a hat," she says without looking up. "Helmet. Flying helmet."

"Huh," I say. "So what are you - a pilot?"

And then she raises her eyes and smiles straight at me, kind of sly.

"Steam Girl," she says.

"What's Steam Girl?"

Then Mrs. Hendricks starts shouting, and the whole cla.s.s shuts up.

That afternoon she's waiting for me by the school gate. I check that no one's watching before say I h.e.l.lo.

"Here," she says, handing me the notebook. It's a cheap school exercise book, with a creased cover and fraying corners. On the first page is a t.i.tle, in big blue letters: STEAM GIRL.

Below that is a drawing of a slimmer, prettier version of the girl in front of me: blue dress, leather jacket, lace-up boots, flying helmet, and goggles. But in the drawing it looks awesome instead of, well, weird.

"Did you do this?" I say. "It's pretty good."

"Thanks." She reaches over and turns the pages. There are more drawings and diagrams: a flying ship shaped like a cigar, people in old-fashioned diving suits swimming through s.p.a.ce, strange alien landscapes, strange clockwork gadgets, and of course, Steam Girl - leaping from the airship, fighting off monsters, laughing and smiling. . . .

"So who's Steam Girl?" I ask.

"She's an adventurer," she says. "Well, her father's an adventurer, and an explorer and scientist. But she goes everywhere with him, in their experimental steam-powered airship, the Martian Rose."