He pauses. Just for a second.

"Being crazy and being prepared," he says, "are the same thing when the world ends."

He keeps walking. We follow. The tunnel goes deeper. The air gets hotter.

But the deeper we go, the more I look at the walls. The gray glow isn't magma. It's... moving.

"Garrick," I say. "The walls."

"I know," he says. "Don't touch them."

"What are they?"

"Bugs. — He doesn't stop walking. — Tiny ones. Smaller than bacteria. They ate the surface. That's why the ground is gray. That's why the sky burned. They eat everything. Metal. Stone. Flesh."

I look at my gloves. At the gray dust from the crater.

"And down here?"

"Too hot for them. — He points deeper into the tunnel. — The core keeps them away. That's why I dug here. The deeper we go, the safer we are."

Bukh stumbles. Looks at his boots. "So we were standing in... bugs?"

"Whale shit," Garrick says. "And the whale ate something bad. Now the shit is alive. And it eats. And it looks like ash."

We walk faster. The gray dust on the walls starts to shift. To move toward us.

"Run," Garrick says.

We run. The tunnel goes deeper. The heat gets worse. The gray dust follows.

And then — we stop.

Ahead. A door. Huge. Metal. Not stone. Metal. And around it — pillars. Gleaming. Untouched by the gray dust.