The Battle of the Labyrinth is a 2008 fantasy-adventure novel based on Greek mythology and the fourth novel in the Percy Jackson & the Olympians series by Rick Riordan. Fictional demigod Percy Jackson, who is fifteen years old by the end of the book, tries to stop Luke Castellan and his army from invading Camp Half-Blood by navigating Daedalus's labyrinth. It was released on May 6, 2008 in the US and Canada.