The Sea of Monsters

Book Detail

The Sea of Monsters, published by Miramax Books in 2006, is the second installment of Rick Riordan’s Percy Jackson and the Olympians fantasy adventure series for young readers. The novel begins the summer after the first book in the series, The Lightning Thief, ends and follows returning heroes Percy Jackson and Annabeth Chase on a quest to save Camp Half Blood. The Sea of Monsters was a New York Times best seller and Book Sense Top Ten Summer Pick. It also won the YALSA Best Book of 2007, Best Fantasy Sequel of 2006 from Kirkus Reviews, and a Barnes and Noble Best Children's Book of 2006. Having taught Greek mythology at the middle-school level, Rick Riordan used his vast knowledge of stories and figures from myth as inspiration for the Percy Jackson series.

Series Detail

The Percy Jackson and the Olympians series draws from Greek mythology and traces Percy's journey to accept and explore his powers as a demigod, the child of a human and a god. The Sea of Monsters is the second book in the series, following The Lightning Thief (2005), and preceding The Titan's Curse (2007), The Battle of the Labyrinth (2008), The Last Olympian (2009), The Chalice of the Gods (2023), and Wrath of the Triple Goddess (2024). The Percy Jackson and the Olympians series has also inspired several other series by Riordan, including The Heroes of Olympus, The Trials of Apollo, and the Camp Half-Blood Chronicles.

Film & Television Adaptations

The Sea of Monsters was adapted into a feature film in 2013 as a sequel to the 2010 film adaptation of The Lightning Thief. It is also the inspiration for the second season of Disney's television adaptation of the Percy Jackson and the Olympians series.

This guide follows the First Hyperion Paperbacks Edition (2007) of The Sea of Monsters.

Plot Summary

The Sea of Monsters opens on Percy Jackson’s last day of seventh grade and the day he is supposed to return to Camp Half Blood for a second summer. After Percy wakes from a dream in which his friend Grover Underwood was chased by a monster, his mom tells him they aren’t going to camp later, promising to give him more information after school. Upset at the news and concerned about his dream, Percy reluctantly agrees and heads to school, where he spends the day defending his friend Tyson from the school bullies. During gym class, a group of unfamiliar bully kids transform into Laistrygonian giants and attack Percy. With the help of Tyson and Annabeth, Percy defeats the monsters, leaving the school building in flames. Annabeth has also been having strange dreams about trouble at camp. She, Percy, and Tyson head upstate.

At camp, the three find a group of warriors holding off an attack by monsters. Percy and Annabeth help defeat the monsters and learn that Thalia’s tree, which protects the camp, has been poisoned. In addition, the camp has a new activities director who dislikes Percy and wants nothing to do with the trouble surrounding the tree.

Over the next few days, more monsters attack, and Percy has another disturbing dream about Grover. In the dream, Grover is being held captive on an island in the Sea of Monsters by the cyclops Polyphemus, who has the Golden Fleece—the only magic strong enough to reverse the poison affecting Thalia’s tree. Percy and Annabeth pressure the new director into assigning a quest to find the Fleece, which he gives to Percy’s enemy Clarisse La Rue, a daughter of Ares. Feeling like they have to do something, Percy, Annabeth, and Tyson sneak away from camp and set out to find Grover and the Fleece.

At sea, Percy discovers new water-related abilities from his father, Poseidon (the god of the sea), including a nautical sense of direction which helps him set a course for Polyphemus’s island. The group encounters Luke Castellan, a camper who went rogue at the end of The Lightning Thief, and learn that he poisoned the tree on the orders of Kronos (titan father of the gods). Running from Luke, Percy and his friends join forces with Clarisse and enter the Sea of Monsters.

The Sea of Monsters presents challenges, both physical and emotional. After an encounter with the sea’s guardians, the group is separated, and it appears Tyson didn’t survive. Grief-stricken Percy and Annabeth barely escape from one threat after another until they finally reach Polyphemus’s island, where they find Clarisse, Grover, and Tyson alive. Polyphemus injures Annabeth, but the group manages to escape alive and with the Fleece.

They arrive back at camp just in time to save Thalia's tree. The Golden Fleece revives camp and leaches the poison from the land. Amidst border patrol and a chariot race, Percy enjoys his summer. Tyson leaves to spend time in the cyclops forges, and Percy receives a visit from Hermes (the messenger god), who delivers a note from Poseidon that tells Percy to be ready. The following night, a panicked Grover wakes Percy. They run out to the tree, where a girl lays unconscious beneath its branches. The girl is Thalia—the Fleece expelled her from the tree, and she is once again alive.