Percy Jackson and Charles Beckendorf infiltrate Kronos's cruise ship, detonate it with Greek fire, but Beckendorf dies before he can escape.

Percy wakes up in Poseidon's underwater palace and learns the god is at war with the Titan Oceanus.

The Oracle of Delphi delivers the Great Prophecy to Percy, stating a single choice will end his days.

Percy and Nico di Angelo visit Luke's mother May Castellan in Connecticut to learn about Luke's past.

Percy uses his empathy link with Grover to wake the satyr from a two-month magical sleep in Central Park.

Percy bathes in the River Styx and becomes invulnerable everywhere except the small of his back.

Percy takes command of forty demigod campers at the Empire State Building to defend Manhattan from Kronos's army.

Thalia Grace arrives with the Hunters of Artemis to reinforce the demigods defending Manhattan.

Kronos advances on the Williamsburg Bridge, injuring Annabeth, and Percy collapses the bridge to drive the army back.

Rachel Dare arrives in wartime Manhattan to deliver the message that Percy is not the hero in the Prophecy.

Silena Beauregard confesses to being Kronos's spy, then dies after fighting disguised as Clarisse against the drakon.

Nico arrives with Hades and an army of the dead to aid the Olympians against Kronos.

Annabeth connects to Luke's spirit inside Kronos, and Luke stabs himself with Backbiter, killing Kronos and himself.

Zeus offers Percy immortality, but Percy refuses and demands all gods claim their demigod children by age thirteen.

Rachel becomes the new Oracle of Delphi, and Percy and Annabeth confess their feelings and share a kiss.

Percy and Beckendorf sacrifice themselves to destroy Kronos's ship, launching the final phase of the Titan war. Percy gains invulnerability from the River Styx and leads demigod forces to defend Manhattan against Kronos's advancing army. After fierce battles across the city, Rachel delivers the revelation that Percy is not the true hero of the Prophecy. Silena's sacrifice and Hades's arrival shift the momentum of the battle before Percy and his allies storm Olympus itself. Annabeth ultimately reaches Luke's trapped spirit within Kronos, and Luke sacrifices himself to destroy the Titan lord and fulfill the Prophecy. Percy refuses godhood and instead secures lasting change for demigods, while he and Annabeth finally confess their feelings for each other.

The headline events of Percy's battle to save Olympus from Kronos.

Percy fights telkhines and defeats a giant crab aboard Kronos's ship before escaping overboard into the sea.

Percy meets Poseidon's immortal wife Amphitrite and merman son Triton at the underwater palace.

Silena Beauregard breaks down in tears at the Big House when she realizes Charles Beckendorf has died.

Clarisse La Rue storms out of the war council, refusing to let the Ares cabin participate in the battle.

Chiron uses Iris's magic to show the war council a vision of the monster Typhon advancing toward New York.

Mrs. O'Leary uses shadow travel to transport Percy and Nico from Camp Half-Blood to Westport, Connecticut.

Hestia appears outside May Castellan's house, provides Percy and Nico a warm meal, and gives her blessing for the fight.

Percy tells his mother Sally and stepfather Paul about the war, and Sally asks for a blue signal if he survives.

Hades reveals to Nico that he froze Nico and his sister Bianca during World War II to protect them.

Annabeth wakes a bronze automaton statue in a Manhattan park and sends it to activate others across the sleeping city.

Percy jumps into the river and gives Poseidon's sand dollars to the river gods in exchange for their help.

Percy defeats the Titan Hyperion near the Reservoir, and Grover commands roots to trap Hyperion permanently.

Chiron's centaur relatives, the Party Ponies, arrive unexpectedly in Manhattan to help fight Kronos's retreating army.

The real Clarisse La Rue arrives and kills the Lydian drakon by stabbing it in the eye with her spear.

Poseidon leads his army out of the sea and helps the Olympians defeat Typhon near the end of the battle.

The opening battles on Kronos's ship and at Poseidon's palace reveal the full scale of the war against the Titans. Back at camp, the news of Beckendorf's death and Clarisse's refusal to fight threaten the demigods' chances of success. Percy gathers crucial allies and resources by visiting May Castellan, recruiting the river gods, and unleashing Daedalus's automatons across Manhattan. The fighting in Central Park and along the city's streets tests every demigod and creature fighting for the Olympians. Unexpected reinforcements, including the Party Ponies and Clarisse herself, prove decisive in turning the tide. The final blow against Typhon comes when Poseidon's army rises from the sea, ensuring Olympus itself can be defended.

The supporting battles, discoveries, and alliances that shaped the war.

Percy reads the Great Prophecy aloud to the war council and reveals he suspects a spy exists at camp.

Nico di Angelo proposes making Percy invulnerable by bathing him in the River Styx as the plan to defeat Kronos.

Nico reveals he made a deal with Hades to bring Percy to the Underworld in exchange for information about his past.

Hades imprisons Percy in the Underworld dungeon to prevent Percy from fulfilling the Prophecy so Nico can instead.

Nico rescues Percy from Hades's dungeon by making the wall vanish and putting the skeletal guards to sleep.

The ghost of Achilles warns Percy at the River Styx that invulnerability will seal his doom regardless of what follows.

Hestia shows Percy a vision of young Luke, Thalia, and Annabeth meeting as runaway children and forming a chosen family.

Annabeth throws herself in front of an enemy blow to protect the vulnerable spot on Percy's lower back.

Annabeth tells Percy that Luke proposed running away with her before joining Kronos, but she refused him.

Percy dreams of Zeus ordering a hotel explosion that kills Nico's mother Maria, and Hades cursing the Oracle of Delphi.

Prometheus shows Percy a vision of Luke's first meeting with Hermes, revealing Hermes already knew of Luke's dark fate.

Percy entrusts Pandora's jar to Hestia rather than open it, committing to fight on without surrendering to Kronos.

Kronos's scythe transforms into Luke's sword Backbiter during the final confrontation in the throne room of Olympus.

Percy convinces Ethan Nakamura that supporting Kronos is wrong, and Ethan attacks Kronos but is defeated and falls.

Percy refuses Zeus's offer of immortality and demands all gods claim and recognize their demigod children by age thirteen.

Percy's acceptance of the Great Prophecy and Nico's plan to bathe him in the River Styx set the entire final act in motion. Hades's attempt to imprison Percy and redirect the Prophecy to Nico reveals how much is at stake and how fragile the plan truly is. Key visions of Luke's childhood, his mother's fate, and Hermes's foreknowledge reframe Luke from enemy to tragic figure whose redemption slowly becomes possible. On the battlefield, Annabeth's sacrifice to protect Percy's weak spot and her shared history with Luke become the emotional foundation for the final confrontation in the throne room. Percy's decision to trust Hestia with Pandora's jar and his ability to turn Ethan against Kronos prove that choices, not fate, determine outcomes. When Luke fulfills the Prophecy himself, it validates Percy's rejection of predestination and his choice to remain a demigod rather than accept immortality.