“If your algae dies, do you keep working with the dead cells?” Valerie asked, soft. Her pupils were wide in the orange glow. She didn’t blink. “I’ve tried every option. Run every other scenario. They’ll notice, soon, that it’s developed from Seventh Disease.” No one on board had ever come down with the childhood disease—the oldest people who had it were probably only about nineteen or twenty. Naomi remembered seeing photos of the red splotches across children’s skin, larger than chicken pox sores but just as itchy. A few years ago, they’d developed a vaccine they’d started giving children, but they hadn’t bothered with adults. The illness, unlike chicken pox, was milder in adults than children.

Hart blinked fast, making the same connections. “Oh, God.”

Naomi struggled to keep up. “You’re killing the adults but keeping the children?”

“Some adults will survive,” Valerie said. “Perhaps five per cent.”

Lebedeva squeezed her eyes shut.

“Valerie, you can’t do this,” Naomi said, her throat tight. “You can’t.”

“It’s a tragedy, but I’m being kinder. No drawn-out suffering. No inevitable war and violence as Earth grows hotter and they continue to compete for resources. Brazil has the largest amount of clean water in the world. Think they’ll look after it as well as the Amazon? This will be quick. A few months, no more.” She didn’t blink as she spoke. She had the fervour of a zealot.

Hixon’s head jerked back. None of them wanted to believe Valerie capable of this. Lebedeva moved towards the door of the rec room, her arms crossed, and Naomi couldn’t help notice it was as if she guarded it.

Hart and Hixon’s heads turned to her as the same knowledge dawned.

“How long have you known?” Hixon asked.

Lebedeva’s face was smooth as slate. “Months.” She said the word, heavily, not as if it had been weighing on her, but as a relief that she could finally set it down. She had lied to them, back on the bridge. She’d known about the embryos. About all of it. Was she the one who had turned the comms back on, without the others noticing?

Everything around Naomi shifted. Her vision went close, her skin clammy and cold.

“You’re not killers, either of you,” Naomi tried. “You can’t just stand by and let this happen.”

“This is what’s best for humanity as a species. You’ll see. We’ll be free. No need to worry about Earth following us through. Whichever country has the most money, the most power, the most weapons, would be able to oust us and disrupt our vision.” Valerie’s expression was bright, resplendent.