Demi-god Percy Jackson and his friends must journey into the Sea of Monsters to save their camp. But first Percy will discover a secret that makes him wonder whether being claimed as Poseidon's son is an honor or a cruel joke.

A near-death experience, a horrible incident at school, and a move from Connecticut to Florida have turned seventeen-year-old Pierce's life upside-down, but when she needs him most John Hayden is always there, helping but reminding her of her visit to the Underworld.

Percy padece dislexia y dificultades para concentrarse. Objeto de burlas por inventarse historias fantásticas, ni siquiera él mismo acaba de creérselas hasta el día que los dioses del Olimpo le revelan la verdad. After learning that he is the son of a mortal woman and Poseidon, god of the sea, twelve-year-old Percy is sent to a summer camp for demigods like himself, and joins his new friends on a quest to prevent a war between the gods.