His Dark Materials: the Subtle Knife by Philip Pullman
The second volume in Philip Pullman's incredible HIS DARK MATERIALS trilogy. First published in 1997, and acclaimed as a modern masterpiece, it won the UK's top awards for children's literature. What is he? A friend, or an enemy? He is a murderer. Will has just killed a man. He's on the run. His escape will take him far beyond his own world, to the eerie disquiet of a deserted city, and to a girl, Lyra. Her fate is strangely linked to his own, and together they must find the most powerful weapon in all the worlds...