His dark materials: The Amber Spyglass

Lyra lies sleeping in a cave near a rainbow, drugged into unconsciousness by her mother, Mrs Coulter, whose love for her daughter closely rivals her own ruthless ambition. Now, the latter threatens to overcome the former, as she strives to prevent the events which are dependent on the decisions Lyra is fated to make. Meanwhile, Will-scarred and traumatised after his last, fatal meeting with his father-seeks blindly for her, with only two of Lord Asriel's angels as companions on his dangerous search. The two are fated to meet once more, however, and begin their most treacherous journey. For Lyra owes a great debt, and she must repay it-she must rescue her friend from the Land of the Dead. Neither are prepared for the terrible sacrifice they must endure, or for the universal consequences of their actions. Lyra and Will must play their part in the war between the worlds and heaven...