His Dark Materials is the story of Lyra and Will, children on the cusp of adulthood and living in separate worlds. Brought together by a dimension-traveling knife, the two journey through Lyra's alternate universe to thwart the ambitions of the domineering and oppressive Catholic Church while discovering their own spiritual truths. The stories deal with themes of religious oligarchy, physics, love, coming of age, and the nature of family and God.