Northern Lights by Philip Pullman

Northern Lights (published as The Golden Compass in the US) by Philip Pullman is the first book in the His Dark Materials trilogy, following brave Lyra Belacqua and her daemon in a parallel Oxford as she embarks on a perilous quest to the Arctic to rescue her kidnapped friend, Roger, uncovering a vast conspiracy involving stolen children, armored bears, witch-clans, and a powerful religious authority, all leading to a struggle for the fate of her world and others, exploring profound themes of soul, free will, and knowledge