"The Book of Three" is a fantasy novel by Lloyd Alexander, published in 1964. It is the first book in the Chronicles of Prydain series, which follows the adventures of a young pig-keeper named Taran. Taran dreams of becoming a hero and embarks on a quest to rescue a pig named Henwen, who possesses magical powers. Throughout his journey, Taran encounters various characters, including the warrior Gurgi and the princess Eilonwy. Together, they face challenges and confront the evil warlord Arawn. The story explores themes of bravery, friendship, and the quest for identity.