I really loved this book. Great fantasy. Percy is a half-blood, the son of a mortal woman and Poseidon, god of the sea. He also happens to be the prime suspect in the theft of Zeus' thunderbolt. So Percy and his buds (Annabeth, the daughter of Athena, and Grover, a satyr) set out on their quest to prevent World War II. Really well-written, and not condescending as so many teen books can be.