Percy lives in an apartment building with his mom and his stepdad.
Percy and his mom go to their beach cabin and a storm happens. Not long after Percy's friend from school, Grover, shows up at his door and instead of human legs, he has goat legs.
Grover tells Percy's mom Sally that Pervy has to go "the" camp. Percy gets confused and they get in Percy's, stepdads car and after a while, they see a figure that looked like a bull-man and it killed Percy's mom.
Percy kills the Minotaur (bull-man) and gets to the camp with Grover. Percy gets to the camp and is in the Hermes cabin until he is called by his real dad who was a god. One of the Hermes kids, Luke, is nice to Percy and acts as a friend.
Percy gets called by his father. Percy also gets blamed for stealing a lightning bolt. He has to go to the underworld and save his mom because he learned that one of the gods, Hades, was keeping his mom prisoner.
Percy, his friend Annabeth and Grover figure out that Luke was the lightning thief and they told the gods. The gods stopped fighting and Percy got his mom back.