The first three ramps had soldiers just like the ones he’d seen at the tube station. Prax didn’t bother stopping. At the fourth, a supply tunnel that led from the surface warehouses down toward the reactors, there was nobody. He paused, the scooter silent beneath him. There was a bright acid smell in the air that he couldn’t quite place. Slowly, other details registered. The scorch marks at the wall panel, a smear of something dark along the floor. He heard a distant popping sound that it took three or four long breaths to recognize as gunfire.

Rapidly evolving apparently meant fighting in the tunnels. The image of Mei’s classroom stippled with bullet holes and soaked in children’s blood popped into his mind, as vivid as something he was remembering instead of imagining. The panic he’d felt in the dome came down on him again, but a hundred times worse.

“She’s fine,” he told the plant beside him. “They wouldn’t have a firefight in a day care. There’re kids there.”

The green-black leaves were already starting to wilt. They wouldn’t have a war around children. Or food supplies. Or fragile agricultural domes. His hands were trembling again, but not so badly he couldn’t steer.

The first explosion came just as he was heading down the ramp from seven to level eight along the side of one of the cathedral-huge unfinished caverns where the raw ice of the moon had been left to weep and refreeze, something between a massive green space and a work of art. There was a flash, then a concussion, and the scooter was fishtailing. The wall loomed up fast, and Prax wrenched his leg out of the way before the impact. Above him, he heard voices shouting. Combat troops would be in armor, talking through their radios. At least, he thought they would. The people screaming up there had to be just people. A second explosion gouged the cavern wall, a section of blue-white ice the size of a tractor calving off the roof and falling slowly and inexorably down to the floor, grinding into it. Prax scrambled to keep the scooter upright. His heart felt like it was trying to break out of his rib cage.

On the upper edge of the curving ramp, he saw figures in armor. He didn’t know if they were UN or Mars. One of them turned toward him, lifting a rifle. Prax gunned the scooter, sliding fast down the ramp. The chatter of automatic weapons and the smell of smoke and steam melt followed him.

The school’s doors were closed. He didn’t know if that was ominous or hopeful. He brought the wobbling scooter to a halt, jumped off. His legs felt weak and unsteady. He meant to knock gently on the steel drop door, but his first try split the skin over his knuckle.

“Open up! My daughter’s in there!” He sounded like a madman, but someone inside heard him or saw him on the security monitor. The articulated steel plates of the door shuddered and began to rise. Prax dropped to the ground and scrambled through.

He hadn’t met the new teacher, Miss Carrie, more than a few times, when dropping Mei off or picking her up. She couldn’t have been more than twenty years old and was Belter-tall and thin. He didn’t remember her face being so gray.

The schoolroom was intact, though. The children were in a circle, singing a song about an ant traveling through the solar system, with rhymes for all the major asteroid bodies. There was no blood, no bullet holes, but the smell of burning plastic was seeping through the vents. He had to get Mei someplace safe. He wasn’t sure where that would be. He looked at the circle of children, trying to pick out her face, her hair.

“Mei’s not here, sir,” Miss Carrie said, her voice tight and breathy at the same time. “Her mother got her this morning.”

“This morning?” Prax said, but his mind fastened on her mother. What was Nicola doing on Ganymede? He’d had a message from her two days earlier about the child support judgment; she couldn’t have gotten from Ceres to Ganymede in two days …

“Just after snack,” the teacher said.

“You mean she was evacuated. Someone came and evacuated Mei.”

Another explosion came, shaking the ice. One of the children made a high, frightened sound. The teacher looked from him to the children, then back. When she spoke again, her voice was lower.

“Her mother came just after snack. She took Mei with her. She hasn’t been here all day.”

Prax pulled up his hand terminal. The connection was still dead, but his wallpaper was a picture from Mei’s first birthday, back when things were still good. Lifetimes ago. He held up the picture and pointed at Nicola, laughing and dangling the doughy, delighted bundle that had been Mei.

“Her?” Prax said. “She was here?”

The confusion in the teacher’s face answered him. There’d been a mistake. Someone—a new nanny or a social worker or something—had come to pick up a kid and gotten the wrong one.

“She was on the computer,” the teacher said. “She was in the system. It showed her.”

The lights flickered. The smell of smoke was getting stronger, and the air recyclers were humming loudly, popping and crackling as they struggled to suck out the volatile particulates. A boy whose name Prax should have known whimpered, and the teacher reflexively tried to turn toward him. Prax took her elbow and wrenched her back.

“No, you made a mistake,” he said. “Who did you give Mei to?”

“The system said it was her mother! She had identification. It cleared her.”

A stutter of muted gunfire came from the hallway. Someone was screaming outside, and then the kids started to shriek. The teacher pulled her arm away. Something banged against the drop door.

“She was about thirty. Dark hair, dark eyes. She had a doctor with her, she was in the system, and Mei didn’t make any kind of fuss about it.”

“Did they take her medicine?” he asked. “Did they take her medicine?”

“No. I don’t know. I don’t think so.”

Without meaning to, Prax shook the woman. Only once, but hard. If Mei didn’t have her medicine, she’d already missed her midday dose. She might make it as long as morning before her immune system started shutting down.

“Show me,” Prax said. “Show me the picture. The woman who took her.”

“I can’t! The system’s down!” the teacher shouted. “They’re killing people in the hallway!”

The circle of children dissolved, screams riding on the backs of screams. The teacher was crying, her hands pressed to her face. Her skin had an almost blue cast to it. He could feel the raw animal panic leaping through his brain. The calm that fell on him didn’t take away from it.