Infernal Devices (Mortal Engines, Book 3)

The derelict city of Anchorage has settled on the edge of the land that was once America. Tom Natsworthy and Hester Shaw are happy in the safety of a static settlement, but their daughter, Wren, is desperate for adventure. A dangerously charming submarine pirate offers her an escape, but wants something in return--Wren must steal the mysterious Tin Book.