Quick recap
Apollo, in Lester's body, enters the Labyrinth with Meg and the satyr Grover to find the third emperor of the Triumvirate. The emperor is Caligula, and the path leads Apollo to Meg's old home in Palm Springs. Jason Grace and Piper join the group, and a prophecy warns that one of them won't return. They steal the emperor's shoes, and the escape costs dearly. Without Jason, Apollo and Meg still have to solve the riddles of the Sibyl of the Labyrinth, face the sorceress Medea and find the source of the heat burning the southern United States.

