After the fight on the Santa Monica beach, the police and reporters accept a false mortal explanation that casts Percy, Annabeth, and Grover as kidnapping victims rather than criminals. The trio uses that story to get plane tickets to New York, and Percy endures the flight in fear of Zeus. At La Guardia, Annabeth uses her invisibility cap to distract reporters, and Percy sends Annabeth and Grover back to Camp Half-Blood while Percy goes alone to finish the quest.

Percy reaches the Empire State Building, gains access to Olympus by showing the master bolt, and travels through the gods' city to the throne room. There, Percy kneels before Poseidon and tells Zeus the full truth, returning the bolt and explaining Ares's role. Percy also warns that Ares was being manipulated by an older evil connected to Tartarus, and Percy names Kronos as the force trying to provoke war among the gods.

Zeus accepts the bolt, decides Percy is telling the truth, and spares Percy for the sake of peace, though Zeus openly distrusts him and refuses to pursue the warning about Kronos. After Zeus leaves, Poseidon confirms that Kronos still exists in torment and can influence dreams, but Poseidon will not challenge Zeus's decision to end the discussion. Poseidon then tells Percy that Sally has been returned by Hades and warns Percy that a package waiting at home will force an important choice. Before Percy leaves, Poseidon finally offers a brief but sincere acknowledgment, telling Percy that he did well and is truly his son.

Back in Manhattan, Percy reunites with Sally, who has only just returned and knows nothing since the Minotaur attack. Sally explains that Gabe has forced her back to work and is furious over Percy's television stunt promising free appliances. When Percy enters the apartment, Percy sees how completely Gabe dominates the home, watches Gabe threaten Sally, and realizes Gabe has physically abused her. Percy wants to attack Gabe but cannot use Riptide on a mortal, so Sally leads Percy to his room.

In Percy's room, a package from Olympus appears: Medusa's head, returned to sender. Percy realizes Poseidon meant Percy could use it to remove Gabe permanently, and Percy offers to solve the problem for Sally. Sally refuses, insisting that she must reclaim her own life and courage rather than let a god or Percy make the choice for her. Percy leaves the box behind for her, says goodbye, and heads back toward Half-Blood Hill, encouraged by the sight of Sally finally looking ready to stand up to Gabe herself.