The Sea of Monsters is a fantasy-adventure novel based on Greek mythology. It was written by Rick Riordan and published in 2006. It is the second novel in the "Percy Jackson & the Olympians" series and is the sequel to "The Lightning Thief". This book is about the adventures of thirteen-year-old demigod Percy Jackson. It describes how he and his friends rescue his satyr friend Grover from the Cyclops Polyphemus. They also save Camp Half-Blood, a summer camp for demigods, from a Titan attack. They bring the Golden Fleece from Polyphemus' island which cures Thalia's poisoned pine tree, that protected the camp.