For questions about the "His Dark Materials" trilogy of fantasy novels, coming together to form an epic, by Philip Pullman comprising Northern Lights (1995, published as The Golden Compass in North America), The Subtle Knife (1997), and The Amber Spyglass (2000). Use with the relevant book tag where appropriate.
His Dark Materials synopsis:
In The Golden Compass, readers meet 11-year-old Lyra Belacqua, a precocious orphan growing up within the precincts of Jordan College in Oxford, England. It quickly becomes clear that Lyra's Oxford is not precisely like our own—nor is her world. In Lyra's world, everyone has a personal dæmon, a lifelong animal familiar. This is a world in which science, theology and magic are closely intertwined.
In The Subtle Knife, readers are introduced to Will Parry, a young boy living in modern-day Oxford, England. Will is only twelve years old, but he bears the responsibilities of an adult. Following the disappearance of his explorer-father, John Parry, during an expedition in the North, Will became parent, provider and protector to his frail, confused mother. And it's in protecting her that he becomes a murderer, too: he accidentally kills a man who breaks into their home to steal valuable letters written by John Parry. After placing his mother in the care of a kind friend, Will takes those letters and sets off to discover the truth about his father.
The Amber Spyglass brings the intrigue of The Golden Compass and The Subtle Knife to a heartstopping close, marking the third and final volume as the most powerful of the trilogy. Along with the return of Lyra, Will, Mrs. Coulter, Lord Asriel, Dr. Mary Malone, and Iorek Byrnison the armored bear, The Amber Spyglass introduces a host of new characters: the Mulefa, mysterious wheeled creatures with the power to see Dust; Gallivespian Lord Roke, a hand-high spy-master to Lord Asriel; and Metatron, a fierce and mighty angel. And this final volume brings startling revelations, too: the painful price Lyra must pay to walk through the land of the dead, the haunting power of Dr. Malone's amber spyglass, and the names of who will live—and who will die—for love. And all the while, war rages with the Kingdom of Heaven, a brutal battle that—in its shocking outcome—will reveal the secret of Dust.