The Lightning Thief is a 2005 fantasy/adventure novel based on Greek mythology, the first young adult novel written by author Rick Riordan. It is the first book in the Percy Jackson and the Olympians series, which charts the adventures of modern day twelve-year-old Percy Jackson as he discovers he is a demigod, the son of a mortal woman and the Greek god Poseidon. Percy and his friends go on a quest to prevent an apocalyptic war between the Greek gods Zeus, Poseidon and Hades.