The opening volume of Philip Reeve's monumental fantasy series filled with airships and pirates, bounty hunters and aeronauts - and moving cities. No one expected an assassination. When the girl with the cloth over her face pulls out a knife to kill London's Chief Historian, Thaddeus Valentine, the young assistant Tom saves his life at the last moment. He chases the girl, who escapes through a disposal chute into the Outlands. That Valentine, instead of thanking his savior, immediately throws the boy out as well, was something no one could have anticipated. Thus begins Tom's adventurous odyssey through the Great Hunting Grounds back to London. He is accompanied by the unwavering Hester Shaw, who is determined to avenge the murder of her parents. They encounter slave traders and pirates along the way.