Spring of 1924 found Tommy O'Brien standing in the Irish enclave on Chicago's South Side, watching the snow melt into streets that would never again carry the boots of fathers and mothers and teachers. The Influenza's Aftermath had taken them in three days--not the dramatic death rattle of fiction, but the quiet surrender of bodies that simply forgot how to wake up. Tommy's parents were among the forgotten. His younger sister was not. She was five. She would live.

Fifty of them gathered at Chicago City Hall--fifty children between the ages of ten and eighteen, drawn from orphanages, from working-class tenements, from the children of dead professors and dead factory owners and dead everyone. Dr. Finch, seventeen, a Chicago University prep student with eyes that saw the world as equations, unrolled a blackboard and began to write. "Rational nation-building," he said. "We apply scientific method to governance. We optimize. We survive."

Clara Jenkins, fourteen, daughter of a schoolteacher, put her hand on the youngest child's shoulder. "We also feed them," she said. "And we teach them. And we make sure they sleep. Science doesn't cover everything, Dr. Finch."

They called themselves the New America. Not a nation yet--an experiment. Tommy, fifteen, son of Irish immigrants who had come to Chicago chasing the dream, was chosen as Coordinator. Not leader. Coordinator. "We don't need a leader," Dr. Finch had calculated. "We need a connector. Someone who can link the rational systems with the human ones." Tommy wasn't sure he understood the distinction, but he nodded anyway.

By summer, the experiment had gilded edges. Jazz poured from basement speakeasies onto State Street. The children had found adult cars and learned to drive them--badly, with a series of spectacular collisions that Dr. Finch logged in his ledger with mathematical detachment. Clara's school taught reading, arithmetic, and, as she put it, "how to be a good person." Tommy organized the Utopia Exposition on the shores of Lake Michigan, where the children displayed their achievements: a functioning power plant, a hospital with three doctors and two nurses (both teenagers), a library built from salvaged books.

The Rational Tower was the exposition's centerpiece. Dr. Finch's masterpiece--a building designed not by architects but by mathematics. "Height determined by structural optimization algorithms," he told the crowd of fifty children and one very confused seagull. "Every floor calculated. Every beam placed according to load-bearing equations."

Tommy stood beside the tower and felt something he could not name. Hope? Pride? The warm golden glow of a dream that might actually work? He couldn't tell. The lake shimmered behind him, and the city rose around him, and for one perfect moment, he believed that the adults' world had not died--it had been reborn in smaller, cleaner hands.

He didn't see Dr. Finch in the back room, calculating.

The ledger was thin and black and contained everything. Food rations. Power output. Student attendance. And then, on a page marked Population Optimization, the numbers that made Tommy's stomach turn. Fifty children. Optimal survival probability: 73 percent. Thirty-eight children. Optimal survival probability: 91 percent.

He stared at the numbers until they blurred. Thirty-eight. Not fifty. Thirty-eight. The math was impeccable. The math was monstrous.

When he confronted Dr. Finch, the boy looked up from his calculations with the mild annoyance of a mathematician interrupted. "You found the optimization page."

"What is this?" Tommy's voice came out quieter than he intended.

"Survival probability. Based on resource consumption models, retaining fifty gives us a seventy-three percent chance of long-term viability. Retaining thirty-eight gives us ninety-one percent."

"You're deciding who dies."

"I'm deciding who lives. It's mathematics."

Tommy felt cold. "What happened to the ones you optimized?"

"They were relocated to the border. There's a lot of land out there. They can... continue."

Clara heard about it that evening. She came to Tommy's quarters in City Hall with tears in her eyes and fury in her voice. "He's sending children away. He's using math to decide who gets to stay and who gets to go."

"He's trying to save us," Tommy said, but the words tasted like ash.

"Saving whom?" Clara's voice cracked. "The ones who stay? Or the ones who do the saving?"

Then came Mr. Sterling, eighteen, son of a Wall Street banker, philosopher in a boy's body. He proposed the New Continent Experiment: trade the Midwest territory to a juvenile civilization on the other side of the Pacific, in exchange for technology and knowledge.

"From a resource optimization perspective, this is the optimal solution," Dr. Finch said immediately.

"Land is not a resource," Clara said. "Land is home."

Tommy stood on the shore of Lake Michigan that night, the exchange proposal in his pocket, the Rational Tower glowing behind him like a golden tomb. He thought of his parents--Irish immigrants who had come to Chicago chasing the American Dream. Now the American Dream had become a mathematical equation. Fifty children. Thirty-eight children. The difference was eighteen percent.

Some things, he realized, cannot be calculated. Not home. Not hope. Not the tears of a fourteen-year-old girl on the shore of a lake that stretches toward an unknown opposite shore.

He folded the proposal and put it back in his pocket. He didn't know if the exchange was right. But he knew this: utopia is not built. Utopia is chosen. And every choice means losing something.

The jazz played somewhere in the distance. The lake shimmered. And Tommy O'Brien, son of Irish immigrants, stood on the shore and wondered if the golden dream was a dream at all, or just gilded math wearing a human face.