Percy's mom was send to hell by a minotaur. Annabeth, Percy, and Grover set out to the underworld to save Percy's mother. They are helped by Luke, who's dad is Hermies.
This move was good because of the action, suspense, and mystery. I loved learning about all the gods and fighting scenes. I found it interesting learning the history and powers of all the god. Even thought some people gave this movie a bad movie review, it was still a great movie and you should go see it.
To see how the movie compares to the books, read Rubina's story.