After learning that the father he never knew is Poseidon, God of the Sea, Percy Jackson is transferred from boarding school to Camp Half-Blood, a summer camp for demigods, and becomes involved in a quest to prevent a war between the gods.
When Camp Half-Blood, the only safe haven for demigods, comes close to being overrun by mythological monsters, Percy must find his best friend Grover, who is prisoner on an island in the Bermuda Triangle, and then set out to save the Camp.
The long-awaited prophecy surrounding Percy Jackson's sixteenth birthday unfolds as he leads an army of young demigods to stop Kronos in his advance on New York City, while the Olympians struggle to contain the rampaging monster, Typhon.