“Then we die here, on the asphalt,” she said, folding the map. “Or we die walking. At least walking is a verb.”

Day ten. They crested a ridge of dead pines and saw it: a narrow-gauge rail line, surprisingly clean of debris, running along the base of a valley. And on the tracks, a single locomotive—a vintage diesel-electric, its yellow paint faded but intact. Black smoke chugged from its stack. Figures moved around it. Living figures.

“Does it still run?” Marcus asked.

They left at dawn.