The Battle of the Labyrinth is a 2008 fantasy-adventure novel based on Greek mythology and the fourth book in the "Percy Jackson & the Olympians" series by Rick Riordan. Demigod Percy Jackson, who is almost fifteen years old, tries to stop Luke 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.