He looked at her, looked over at her two friends. “There’s just three of you,” he said sadly. “I’m sorry.”

He turned away, in shame, and walked faster.

“Yuguo,” she said to his back. “My name is Lifen.”

“It’s game theory,” Xiaobo said.

They were crowded into the maintenance room of the Chemistry Building, with its pipes and concrete and dark dinginess. Yuguo sat on an overturned bucket, listening in a funk. It was futile, that’s what it was. It was depressing.

“Prisoner’s Dilemma,” Xiaobo went on.

“Who’s being asked to defect?” Lee asked.

Xiaobo shook his head. “Everyone in China is a defector. Everyone who isn’t out there protesting right now. Doing nothing is defection. Doing nothing is betrayal. And as long as enough of us do nothing, the whole country gets a negative payoff. We get the government we deserve.”

Longwei nodded. “All that’s required for evil to triumph is that good men do nothing,” he said.

Xiaobo smiled. “When bad men combine,” he quoted. “The good must combine; else they will fall one by one. Edmund Burke. Prisoner’s Dilemma by any other name.”

“So do we all go join the protests?” Yuguo asked quietly.

Lee leaned back. “You know what happens to cooperators in Prisoner’s Dilemma. Someone else defects. You get it worse.”

It was the same old problem. No one wanted to go first, or even fourth, or even four hundredth. No one wanted to be in the first wave.

There was a sound at the door. Knock-pause-knock-knock-knock-pause-knock.

Lee went to check.

It was Wei, with a satchel, and a huge smile across his face.

“What have you got there, Wei?” Xiaobo asked.

Wei just grinned wider, opened his bag, and pulled out a vial, which he held up to the light in the center of room.

Within it, silvery fluid swirled, almost with a mind of its own.

Yuguo’s breath caught in his chest.

“Nexus!” Wei said.

The shock hit them all hard. Then the questions came, and the babbling, excited burble of a dozen boys talking over each other.

“Hold on!” Wei said. “I made it in the chemreactor on the third floor, this building. Today. Just now.”

“That’s impossible,” Lee said. “It’s a banned chemical! The chemreactors are all locked down! Just like all the 3D printers and circuit printers!”

“Not anymore,” Wei grinned.

“How much did you make?” Xiaobo asked.

“Not much,” Wei said, casually. “Sixty doses.”

“Sixty!” Lee exclaimed. “You could get the death penalty for that!”

“I could have made thousands,” Wei said, a satisfied look on his face. “Maybe tens of thousands.” He turned the vial end over end in his hand, still holding it aloft, his eyes locked on it. The silver fluid swirled, tendrils of it reaching out, as if taunting Yuguo, taunting him with the utter impossibility of it, with the folly of it, with the complete illegality of it.