The Tin Princess (Sally Lockhart Mystery, Bk. 4)

Detective Sally Lockhart's friend and partiner-in-adventure Jim Taylor has just been hired as a body guard to a princess. But Crown Princess Adelaide of Razkavia is not what you'd expect. She's the slum-girl Jim has been searching for ever since she vanished ten years ago. Now her life is in mortal danger, and together they must battle against unknown enemies in a country where no one can be trusted...