The rebel straightens up, panting. "Nice moves," he says. "Oh, man, remind me not to get in you guys' way."

Ahead, there's fallen rubble in plenty from where 280 collapsed. Moving from rubble chunk to rubble chunk is the only way out of the sea of chemical nastiness. On the other side emergency lighting flickers faintly, and what might be a flare gleams in the darkness. Somewhere beyond that is the bluish-grey glimmer of daylight filtering in again.