The Lightning Thief is a 2005 fantasy-adventure novel by Rick Riordan. It is the first book in the Percy Jackson & the Olympians series and is based on Greek mythology. The book is about a 12-year-old boy named Percy Jackson who discovers he is a demigod, the son of Poseidon and a mortal woman. Percy and his friends try to prevent a war between the Greek gods Zeus, Poseidon, and Hades. See pictures for condition.