The Battle of the Labyrinth is a 2008 fantasy-adventure novel based on Greek mythology; it is the fourth novel in the Percy Jackson & the Olympians series by Rick Riordan. Percy Jackson, a fictional demigod (who is fifteen years old by the end of the book) attempts to stop Luke Castellan and his army from invading Camp Half-Blood through Daedalus's labyrinth by trying to convince the inventor not to give Ariadne's string to Luke.
The Battle of the Labyrinth was published in the U.S. by Hyperion Books for Children, an imprint or division of Disney Publishing (succeeded by the Disney Hyperion imprint). It was released on 6 May 2008, in the US and Canada.
The book opens with Percy Jackson attending freshman orientation at Goode High School, where he sees Rachel Elizabeth Dare, who helps him to recognize and fight two empousai disguised as cheerleaders, Tammi and Kelli. Percy is forced to flee to Camp Half-Blood, while Rachel stays behind. On the way, Percy runs into Annabeth, who is annoyed to find him in the company of a mortal girl. When they reach camp, Percy learns Grover is in trouble from the Council of Cloven Elders for not having made progress finding the god Pan after claiming he felt Pan's presence in New Mexico that winter. Percy also encounters a middle-aged demigod named Quintus, who is the new sword instructor of Camp Half-Blood. Chiron describes the man as "hard to read", a description Percy agrees with.