The day the adults stopped showing up, I stood on the roof of St. Augustine Academy and looked at Manhattan and I realized something: nobody else had noticed.

It was a Tuesday in March, 2031. I had been student body president for eleven months, and my job was mostly boring—organizing food drives, approving club budgets, mediating disputes between the chess club and the debate team about who got the conference room on Fridays.

But on this Tuesday, the teachers did not come.

Ms. Alvarez, who taught AP English, did not come. Mr. Chen, who taught mathematics, did not come. Coach O'Brien—Danny O'Brien, nineteen, teaching PE on a temporary credential because the district was short-staffed—did not come.

At first, we thought it was a sick day. Then a strike. Then a weather emergency. But the sky was blue, the phones worked, and the news on the principal's office TV was talking about something called "Adam Syndrome" in serious, measured voices that made my stomach feel like it had dropped three floors.

By Wednesday, we knew what had happened. By Thursday, we believed it. By Friday, we stopped pretending we were waiting for someone to come fix it.

Adam Syndrome was a genetic condition that affected telomerase-producing cells in adults—specifically, people over thirty. It was rare, the news said. Terrible, but rare. In seventy-two hours, it had spread through the adult population like a quiet fire, burning through hospitals and nursing homes and office buildings and houses across the city and, apparently, across the world.

When the news said "across the world," I looked at the other students standing around me in the hallway—hundreds of us, ages sixteen to eighteen, wearing hoodie and jeans and expressions that ranged from confused to terrified to weirdly calm—and I understood that "across the world" meant "everyone who could tell us what to do is gone."

Priya Patel was the first person who said it out loud. She was sixteen, Indian-American, and the most brilliant computer person I had ever met. She was standing next to me in the hallway, holding her phone with both hands like it was a live grenade, and she said, "The servers are still running."

"What servers?"

"The ones in the basement. The school servers. They have backup power, and I checked—the internet is still up. The cell towers are still up. Everything that runs on electricity is still up. But nobody is managing it."

"Can you manage it?"

"I can try. But if something goes wrong—if a server overheats or a router fails or a power grid fluctuates—I do not know if I can fix it. I know Python. I do not know power grids."

We called a meeting that afternoon in the auditorium. Two hundred students showed up. We had to move to the gym, and three hundred showed up. We had to move to the football field, and five hundred showed up. By the end of the day, maybe eight hundred of the nine hundred students in the school had told us they were coming. The ninth hundred was missing, and we did not know where they were, and that was the first fear we had to deal with.

I stood on the bleachers and I looked out at the sea of faces—faces I recognized from hallways and classrooms and the cafeteria, faces that were now looking at me with an expectation that made my hands shake—and I said the first thing that came into my head.

"We are going to be okay."

I did not believe it. Nobody believed it. But it was the right thing to say, and we needed the right thing.

Coach O'Brien came to see me that evening. He was nineteen, which made him the oldest person in the building by at least a year, which made him, by some arbitrary logic, the closest thing we had to an adult. He had been a teaching assistant for the PE department—a grad student who worked evenings at a gym in Queens and came to class during the day because the credential required it.

He was wearing a sweatshirt and jeans and a face that was trying very hard to look confident and failing.

"Marcus," he said, sitting down on the bleacher next to me. "We need to talk."

"I know."

"The students are looking to you. I can see it. They think you are the leader because you are student body president. And maybe you are. But Marcus—you are seventeen. You are a kid."

"I know."

"I am nineteen. I am also a kid. But I am the oldest person in this building, which means I am the closest thing we have to authority. And I need you to know that I am terrified."

"I am terrified too."

"Good. That means you are paying attention. Here is what I think we need to do. First: food. How much food do we have in the cafeteria?"

I counted. "About three days. Maybe four if we ration."

"Okay. Second: water. Is the water still running?"

"Yes. The pumps are electric, and the power is still on."

"Third: security. Are the doors locked?"

"Some of them. The main entrance is locked. The side exits are not."

"Then we lock the side exits. Not to keep people out. To keep people in. Panic is more dangerous than whatever is happening outside."

We made a plan. It was not a good plan. It was a plan made by seventeen-year-olds and a nineteen-year-old, and it was the best plan we had.

Priya kept the internet running for three days. Then a server overheated in the basement, and she managed to cool it down using the emergency ventilation system, but the stress had visibly taken its toll—she stopped sleeping, stopped eating, and spent eighteen hours a day in the server room, her face lit by the blue glow of monitors, her eyes dark and focused and increasingly distant.

I managed the food distribution. This turned out to be harder than I expected. Not because of the logistics—rationing three days of food over an indefinite period was simple arithmetic—but because of the people. Some students wanted to hoard. Some wanted to protest. Some wanted to leave the building and "find their families."

I held a meeting on the football field every morning at eight o'clock. I stood on the bleachers and I told them what I knew (not much) and what I was doing about it (a lot, or trying to) and I asked them to trust me. Most days, most of them did. Some days, not enough.

The first crisis came on the fifth day. A group of about thirty students, led by a senior named Danny Ruiz (no relation to Coach O'Brien, though he liked to remind everyone that they shared a name), decided to leave the school. They had packed backpacks with food and water and flashlights, and they were standing at the main entrance, waiting for someone to unlock the door.

I unlocked it.

"I am not stopping you," I told them. "But I want you to know something. Outside that door, the world is different now. You do not know what is happening. You do not know if the power will stay on or if the water will keep running or if there are other people out there who are as scared as you are. You can leave. But do not come back and blame us for not warning you."

Danny Ruiz looked at me for a long moment. Then he nodded once and walked out the door with his thirty backpacks. The door locked behind them with a sound that felt final.

Two of them came back three days later—hungry, scared, and alone. The other twenty-eight did not return. We did not know if they were alive or dead or anywhere at all.

The second crisis came on the twelfth day. The power grid failed.

It was not dramatic. There was no explosion, no smoke, no alarm. One moment the lights were on and the servers were running and the fluorescent tubes in the hallway were humming their electric buzz, and the next moment everything was dark and silent and the servers in the basement had stopped spinning.

Priya was the first person downstairs. She came back up five minutes later and said, "The backup generators kicked in. But they only power the essentials—emergency lighting, the refrigeration units, one server rack. The rest is offline. I can try to restore more power, but I need help."

I volunteered. Coach O'Brien volunteered. Three other students volunteered. We went downstairs into the server room, and Priya showed us what needed to be done, and we did it—the four of us, working together in the blue glow of the monitors, restoring power to half the building, one switch at a time.

When we finished, it was past midnight. The school was half-lit, half-dark, and the students in the half-lit portion could see each other by flashlight, and the students in the half-dark portion could not see each other at all.

I sat on the basement steps and I caught my breath and Priya sat down next to me. She smelled like sweat and ozone and exhaustion.

"We did good," she said. It was the first time I had heard her smile in days.

"We did okay," I said. "But the grid is fragile. If anything else goes wrong—"

"Then we fix it again."

"With what? We are kids, Priya. We are literally children. We do not know how to fix a power grid."

"We figured it out once. We can figure it out again."

She was right. We were kids. But we were also the only people who knew how to keep the servers running and the food distributed and the doors locked and the panic contained. We were the only authority that existed in a five-mile radius, and that meant being a kid was the job.

On the thirtieth day, I stood on the roof again and looked at Manhattan. The city was quiet. Not dead-quiet, but different-quiet. The streets below were empty. The skyscrapers were dark. The only movement I could see was in Central Park, where deer were walking through the grass like they had always been there and were just now remembering that they were deer.

Priya came up to the roof and stood beside me. She had lost weight—five pounds, maybe ten—and her hair was uncharacteristically messy, but her eyes were still bright and focused and alive.

"How are the servers?" I asked.

"Running. Not great, but running. I have a plan to build a solar array on the roof. It will not power everything, but it will power the essentials. I need help. You are going to give me four people."

"I will give you six."

She smiled. "You are getting good at this, Marcus."

"I am getting better at pretending I know what I am doing."

"That is all any of us are doing."

We stood on the roof and we watched the sunset over Manhattan—the skyscrapers turning gold and then orange and then purple and then black—and I thought about what it meant to be seventeen years old in a world that had no adults.

It meant being afraid. It meant making mistakes. It meant not knowing the answer and pretending you did anyway.

It also meant, apparently, keeping a city alive.

"Not today," I said. "But maybe tomorrow."