When they come across a wrecked train, at first it's a welcome distraction but what Sham finds in the derelict, a kind of treasure map indicating a mythical place untouched by iron rails, leads to considerably more than he'd bargained for. Soon he's hunted on all sides, by pirates, trainsfolk, monsters, and salvage-scrabblers. It might not be just Sham's life that's about to change, it could be the whole of the railsea.