The subtle knife

Lyra and Will, her newfound friend, tumble separately into the strange tropical otherworld of Citta'€gazze, "the city of magpies", where adults are curiously absent and children run wild. Here their lives become inextricably entwined when Lyra's alethiometer gives her a simple command: find Will's father. Their search is plagued with obstacles--some familiar and some horribly new and unfathomable--but it eventually brings them closer to Will's father and to the Subtle Knife, a deadly, magical, ancient tool that cuts windows between worlds. Through it all, Will and Lyra find themselves hurtling toward the center of a fierce battle against a force so awesome that leagues of mortals, witches, beasts, and spirits from every world are uniting in fear and anger against it.