The Tin Princess Philip Pullman
Book 4 in the Sally Lockhart Quartet.
Jim Taylor, Sally's oldest friend, is engaged as bodyguard to a princess. But Crown Princess Adelaide of Razkavia 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. This dramatic story of love, loyalty and adventure is the final novel in the quartet.
