Percy, Annabeth, Rachel, Nico, Grover, and Tyson reach Times Square through the Labyrinth and summon Blackjack and other pegasi for the flight to Camp Half-Blood. Rachel cannot go with them, and before leaving she reveals that her wealthy father is a land developer who destroys wilderness, making Pan’s death feel painfully personal to her. Percy reassures Rachel that he judges her by her courage, not her father’s work, and Rachel asks Percy to call her before disappearing into the city.

Nico initially refuses to return to camp because he does not feel welcome, but Annabeth persuades him to come, at least temporarily. At camp, Chiron already fears that Kronos’s forces are close, while Silenus angrily rejects Grover’s announcement that Pan is dead. Chiron delays that argument because the camp is under attack, and the demigods, satyrs, dryads, and cabins prepare their defenses around the Labyrinth entrance.

As the army erupts from the Labyrinth, Laistrygonian giants, serpent women, hellhounds, telekhines, and enemy demigods overwhelm the camp’s traps and formations. Beckendorf’s catapults, Apollo’s archers, Clarisse’s Ares line, Annabeth’s Athena fighters, Chiron, Tyson, and Percy all join the defense. Nico uses his Stygian sword and summons undead warriors to stop serpent women from slipping toward the main camp, but the effort drains him badly.

Percy destroys a hellhound with Greek fire and uses his power over water to put out flames threatening Juniper’s tree. The battle seems briefly balanced until Kampê emerges with Ariadne’s string, terrifying the campers and attacking Percy and Annabeth. Kampê pins them down, but Mrs O’Leary, Daedalus, and Briares arrive from the Labyrinth; Briares crushes Kampê beneath a massive volley of boulders.

Kronos’s forces make one final push and injure Chiron, but Grover suddenly releases a terrible sound of pure panic that sends the entire enemy army stampeding back into the Labyrinth. After the battle, Percy helps revive Nico, who has nearly collapsed from summoning the dead. Daedalus explains that he and Briares came to make amends, gives Annabeth a laptop containing his designs, asks Percy to care for Mrs O’Leary, and allows Nico to release his spirit; because Daedalus’s life sustains the Labyrinth, his death causes the maze to collapse.