This movie is coming out or is out, and it is essentially a modern version of the Greek tale of Perseus, the demi-god son of Poseidon, who goes on an adventure, aided by the Greek Pantheon, and fights mythical creatures (Harpies, Gorgon, etc).
Synopsis: Percy Jackson is a normal, everyday kid in high school, until he meets with Athena, disguised as his teacher, and her daughter, among other people. Athena tells him after school that Zeus's legendary Thunderbolts have been stolen, and that Percy is the son of his brother, Poseidon, god of the Seas. Together with the aid of Athena, Hespheteus (god of weaponsmith/blacksmithing), and Hermes, Percy fights off the evil monsters of Greek Mythology, and uncovers the mystery of the stolen thunderbolts, as he unlocks his demi-god status.