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. Fictional demigod Percy Jackson (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 Luke Ariadne's string.
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, a mortal who can see through the Mist that he met briefly while at the Hoover Dam that winter. At the school orientation assembly, Rachel becomes frightened and ushers him out of the gym and into an abandoned band room. He begins to explain how he is a demigod, but they are interrupted by two empousai disguised as cheerleaders, Tammi and Kelli. Tammi begins to seduce Percy, but he snaps out of it and manages to kill her. Kelli, her mentor, starts toward an approaching tour group as if to attack them, and Percy runs after her, swinging his sword as if to kill her, but she causes a wave of flames that sets fire to the school, while incriminating Percy. 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, and for claiming that he felt Pan's presence in New Mexico(truthfully), and that Annabeth has been working on a secret project with Clarisse, and that it was the reason for Clarisse's absence the summer before. Percy also encounters his brother Tyson and a middle aged demigod named Quintus, the new sword instructor of Camp Half-Blood. Chiron describes the man as "hard to read", a description Percy agrees with. Quintus has an enormous hellhound named Mrs. O'Leary for a pet.