Percy and Blackjack fly over a collapsing Midtown defense as Kronos’s army presses toward the Empire State Building. Percy chooses to land where Annabeth and Athena campers are fighting a Hyperborean giant; with Annabeth distracting the giant, Percy wounds it behind the knee, causing it to freeze and shatter.

For the next hour, Percy and Annabeth rush from block to block, destroying monsters and trying to reinforce weak points, but Kronos’s forces keep replacing their losses. The defenders are pushed back until the entrance to Olympus is only twenty feet behind Percy, while Kronos advances in a golden chariot, rested and confident after letting Percy wear himself down.

Just as Annabeth advises a final retreat to the doorway, hunting horns sound and Chiron arrives with hundreds of Party Pony centaurs. Their chaotic cavalry charge, absurd weapons, and Celestial bronze-laced attacks break Kronos’s army and force it into retreat, though Chiron orders the centaurs to stop before they overextend. The defenders establish a two-block perimeter, buying time but not victory.

Chiron explains that many centaur chapters answered his call, but even with them the defenders cannot protect much territory. Chiron also reports that Typhon has injured Dionysus and Hephaestus and will reach New York within a day, meaning Olympus must hold against Kronos until then despite terrible odds. After Chiron and Thalia leave to strengthen defenses, Percy tells Annabeth about Hestia’s visions of Luke and the possibility that Luke still resists Kronos from inside his own body. Annabeth admits her fear of things falling apart and connects her desire to build lasting monuments with her need for permanence, while Percy warns that Luke has betrayed Annabeth too often.

Percy is suddenly pulled into a rural bar where Dionysus, present through the power of a party, warns him that Olympus’s fall would unravel Western civilization itself. Dionysus says the gods need mortal heroes to save Olympus, reveals that Kronos will soon burn away Luke’s mortal body and assume a deadly Titan form, and asks Percy to protect Pollux. When Percy returns, no time seems to have passed.

Percy then discovers Paul’s Prius with Sally and Paul asleep inside, trapped in Manhattan traffic because they came looking for him. In the backseat is Pandora’s jar, which has followed Percy because it appears when he is weakest and tempts him to surrender hope. Percy decides to move the car and take the jar to Olympus, but a Dare Enterprises helicopter breaks through the barrier, its pilot falling asleep under Morpheus’s enchantment. Annabeth summons Guido the pegasus and urges Percy to help save his friend.