Percy Jackson, a kid who describes himself as a "troubled' kid, sufferes from dyslexia and ADHD which he later finds out are the pros of being a Demi-God. After facing a Fury at Yancy Academy, his mom and his best friend -Grover- take him to Camp Half-Bood where he faces a MInotor who turns his mom into gold sprakles.
Upon Percy's arrival at Camp Half-Blood, he is introduced to everyone in the camp including Luke and Annebeth. After playing in his first "Capture the Flag" event, Percy realizes he is the son of Posidein. He is then introduced to his quest. With the company of Annabeth, daughter of Athena, and his satyr friend Grover, to recover the lost master bolt and prevent war between Zeus and Poseidon. Percy has only had a few days of training, but he has to save the world.
Along the way, Percy and his friends run into many road blocks and conflicts. Venturing through the United states, the trio is faced with battling Medusa at first, then being tricked by Ares at the water park, and almost getting stuck in an eternal cycle at the Lotus Vegas casino. Annebeth and Grover were almost stretched out to death by Procrustes. And finally entering the Underworld to retrieve the bolt from Hades.
Percy and his friends finally arive to Hades to ask for the Master Bolt only to be shocked by their new discovery. Ares, the god of war, had tricked them and placed the lightening bolt in the bag he gave Percy. They were forced to fly back to New York and return the bolt back to Zeus in time.
Percy returns back home and is reunited with his mother (Sally). Gabe is acting worse than before and hits Sally when she delays his dinner. Percy is infuriated by this and wants to take action. He finds the packaged head of Medusa that he had tried to send to Olympus, and realizes that the gods gave it to him so he can get rid of Gabe by turning him to stone. He leaves it to his mother to decide Gabe's fate and returns to the camp.
Everyone at the camp was thrilled to see Percy, Annebeth and Grover have returned all in one piece. Grover is finally granted his searcher's license and heads off to find Pan. Percy is happy that his dad is proud of him and his mom has a chance at new life. After everyone leaves to the camp, Luke takes Percy to the woods to train with him one last time. Luke then reveals to him that he serves Kronos - Lord of the Titans - and was the one who stole the lightening bolt and Hade's helm. He then summons a scorpion to kill Percy and disappears. Percy realizes that Luke was the friend in the prophecy that would brety him and after recovering he makes the decision to hunt him down.