The afternoon begins in celebration. Grover learns that the Council of Cloven Elders is rewarding him with time at camp and new reed pipes, and Percy decides to keep their empathy link so he can help Grover again if danger returns. Chiron also tells Percy that he used the Mist to clear Percy of legal trouble at Meriwether Prep, and Percy calls his mother, who is relieved he is alive and insists he stay at camp to keep training.

That evening, Tyson tells Percy that Poseidon sent him a dream and wants him underwater for the rest of the summer to learn at the Cyclopes’ forges. Percy feels both jealous and heartbroken, but he supports Tyson because the camp will need weapons for the war ahead against Luke and Kronos. Tyson leaves on Rainbow the hippocampus, and Percy is left mourning his brother’s departure while admiring the shield-watch Tyson made for him.

Annabeth and Grover join Percy, and for a moment the three friends are together again as before. During the night, a storm surrounds the coast but cannot enter Camp Half-Blood because the Golden Fleece has restored the camp’s magical borders. Percy still sleeps badly, dreaming first of Kronos mocking the heroes’ victory and then of Poseidon in his underwater palace warning Percy to brace himself.

Before dawn, Grover wakes Percy in panic and drags him toward Half-Blood Hill. Campers gather as rumors spread, and Chiron rushes Percy to the tree, where the Fleece is still hanging and Thalia’s pine looks healthy. Chiron realizes the problem at once: the Fleece did not merely heal the poison in the tree, but removed everything unnatural that had bound it in that form.

Percy first fears Annabeth has been hurt, but Annabeth is kneeling beside an unconscious girl at the foot of the tree. While the others stand back in shock, Percy tries to help the girl, sensing she is a half-blood. When she wakes and identifies herself as Thalia, daughter of Zeus, Percy understands that Kronos poisoned the tree in order to bring another child of the prophecy back into play, changing the stakes of the future for everyone.