The Subtle Knife (His Dark Materials, Book 2)

As the boundaries between worlds begin to dissolve, Lyra and her daemon help Will Parry in his search for his father and for a powerful, magical knife. She had asked: What is he? A friend or an enemy? The alethiometer answered: He is a murderer. When she saw the answer, she relaxed at once. Lyra finds herself in a shimmering, haunted otherworld – Cittàgazze, where soul-eating Spectres stalk the streets and wingbeats of distant angels sound against the sky. But she is not without allies: twelve-year-old Will Parry, fleeing for his life after taking another's, has also stumbled into this strange new realm. On a perilous journey from world to world, Lyra and Will uncover a deadly secret: an object of extraordinary and devastating power. And with every step, they move closer to an even greater threat – and the shattering truth of their own destiny.