Percy returns to Camp Half-Blood from the ocean, where Connor Stoll spots him and sounds the alarm. The campers gather expecting a victory, but Percy’s expression reveals the cost of the mission. Silena Beauregard realizes Charles Beckendorf is dead and breaks down, while Clarisse comforts her and leads her away.

Percy privately tells Chiron and Annabeth about the destruction of the Princess Andromeda and his dream of the Titans, but Percy keeps Nico’s plan secret as promised. Percy also relays Poseidon’s warning about a greater threat and insists that it is time to hear the full Great Prophecy. Chiron reluctantly agrees and sends Annabeth with Percy to retrieve the prophecy from the Oracle in the Big House attic.

In the attic, Annabeth explains that the Oracle’s spirit once passed between living maidens but now remains in a mummy. Instead of speaking, the Oracle holds the written Great Prophecy in a pouch around its neck. Annabeth retrieves it, saying she read it years earlier and still has nightmares about it, and they bring it downstairs to the war council.

At the war council, the senior counselors are already fighting. Clarisse argues with Michael Yew over a disputed claim to loot and, feeling that Ares cabin is disrespected, declares that her cabin will not fight until she gets satisfaction. After Clarisse storms out, Percy reads the Great Prophecy, which says a child of the eldest gods will reach sixteen, see the world in endless sleep, have the hero’s soul reaped by a cursed blade, make a choice that ends his days, and either preserve or destroy Olympus. Percy concludes that the prophecy likely points to his death, though Annabeth and others suggest there may be double meanings.

Percy shifts the council to the spy problem and explains that Kronos knew about the attack and used a silver scythe charm to communicate with someone at camp. The counselors briefly accuse one another, upsetting Silena, until Pollux suggests watching for a matching scythe necklace. Chiron then reveals the larger threat: Typhon has broken free from beneath Mount St. Helens and is moving east toward New York while the Olympian gods try to slow him. Percy suspects Kronos is using Typhon as a distraction and that another attack on Olympus is coming, leaving Camp Half-Blood with an undefended Olympus, a hidden spy, a divided army, and only five days before Percy’s sixteenth birthday.