The story takes place in a different world from reality. In this world, all humans have animal companions called guardian spirits, which are the concrete embodiment of human souls. The heroine Lyra Belacqua grew up in Jordan College in Oxford, England. In her journey to London to find her missing friend Roger, Lyra discovers that a series of children's disappearances are related to the mysterious substance Dust. As the story unfolds, she also discovers dangerous secrets involving Lord Asriel and Marissa Coulter.