The Sea of Monsters (Miramax Books, 2006) is the second installment of Rick Riordan’s Percy Jackson and the Olympians fantasy adventure series for young readers. The book picks up the summer after the prequel, The Lightning Thief, ends and follows returning heroes Percy Jackson and Annabeth Chase on a quest to save Camp Half Blood. It is followed by The Titan's Curse (2007), The Battle of the Labyrinth (2008), and The Last Olympian (2009). The Sea of Monsters was a New York Times and Book Sense National Childrens bestseller, and it won such awards as YALSA Best Book of 2007, Best Fantasy Sequel of 2006 from Kirkus Reviews, and a Barnes and Noble Best Childrens Book of 2006, among others. It was adapted into a feature film in 2013, following the movie of The Lightning Thief. 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. 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 waking from a dream in which his friend Grover Underwood was chased by a monster, Percy’s 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. Percy and Annabeth help defeat the monsters and learn Thalia’s tree, which protects 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. Grover is on an island in the Sea of Monsters being held captive 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 (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 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. A 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 the tree. The Golden Fleece revives camp and leeches 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 (messenger god), who delivers a note from Poseidon that tells Percy only 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.