Percy Jackson struggles to focus on his school work and contain his temper which means that he is often not very far from trouble whilst at boarding school.  However, what he didn't envisage happening was one of his teachers turning into a monster and try to kill him.  At this point, Percy learns that he is a Demi-God.  Half-God and Half-human, Percy is sent to Camp Half Blood where he learns that the father he never knew is in fact Poseidon, God of the Sea.   

Percy, along with his friends a Satyr and the daugther of the Goddess Athena, sets off on a quest to reach the underwold to prevent a catastrophic war between the gods.