After Clarisse kills the drakon, Silena dies in Clarisse's arms. Silena admits she was Kronos's spy: Luke charmed her before she loved Charles Beckendorf, then threatened to expose her and claimed her information would save lives. Silena says Luke promised not to hurt Charles, and Annabeth is shaken by the proof of Luke's cruelty.

Clarisse orders the Ares campers back into the fight, and Annabeth insists they must honor Silena's sacrifice. Clarisse, enraged and grief-stricken, becomes nearly unstoppable under the blessing of Ares. She drives Kronos's forces away from the Empire State Building while dragging the drakon's corpse behind her chariot and challenging Kronos to face her.

Inside the lobby, Percy, Annabeth, Thalia, and the Stoll brothers assess the collapsing defenses. The doorman has vanished, meaning the magical protections around the elevator are weakening, and the Titans can now reach Olympus if they break through. Percy sends the wounded Mrs. O'Leary away on a secret errand for reinforcements, then finds Grover with the dying satyr Leneus, who believes they have won before turning into a laurel sapling.

Percy, Annabeth, and Grover take the elevator to Olympus, where the city is dark, deserted, and filled with wounded demigods, Hunters, satyrs, naiads, and dryads. Grover plants Leneus in the gardens. Annabeth, still devastated by Silena's confession, tells Percy that he was right about Luke, while Percy tries to protect Pollux by asking him to remain with the wounded instead of returning to battle.

In the throne room, Percy finds Rachel holding Pandora's jar and staring at the Hope inside. Hestia tells Rachel that Rachel must let go of distractions to claim her place at the hearth, and Rachel explains to Percy that her connection to Percy was about discovering her true sight, not romance or shared fate. Percy nearly despairs under Prometheus's temptation, but memories of home, camp, friends, and Nico's argument to Hades help him understand that Olympus must be defended as everyone's home.

Percy gives Pandora's jar to Hestia, calling the neglected goddess the last Olympian and trusting Hope to the hearth. Then Percy sits on Poseidon's throne to force a dangerous conversation with his father. Percy persuades Poseidon to abandon the defense of his underwater palace and come to Olympus because Kronos is trying to divide the gods; moments later, Thalia bursts in and warns that Kronos is leading a renewed enemy advance.