The Sea of Monsters is the second installment of the Percy Jackson & the Olympians series. This fantasy-adventure series based on Greek mythology follows the adventures of protagonist Percy Jackson, a demigod descended from the god Poseidon and mortal Sally Jackson. In The Sea of Monsters, 13-year-old Percy and his friends fight to save Camp Half-Blood. Themes explored in the novel include family, coming of age, and good versus evil.