Percy Jackson (Logan Lerman), son of Poseidon, is protected from harm at Camp Half-Blood by a mighty tree, which took root on the spot where Thalia (Paloma Kwiatkowski), daughter of Zeus, gave her life to protect three friends. The tree generates an invisible forcefield that repels evil, allowing only the chosen ones to enter.
In the aftermath of a tournament, a gargantuan bronze bull smashes the forcefield and rampages through the camp almost killing Percy.
Dionysus (Stanley Tucci) and centaur Chiron (Anthony Head) rush to Thalia’s tree and discover someone has poured poison into the bark, leaving the camp open to further attacks. The only artefact which can restore the tree, is the Golden Fleece but this precious item lurks within the Sea of Monsters, otherwise known as the Bermuda Triangle.