As Polyphemus attacks the heroes on the beach, Clarisse, Grover, and the injured Annabeth head for the ship with the Golden Fleece. Polyphemus focuses on Tyson, accusing Tyson of betraying Cyclopes by helping mortals. Tyson rejects Polyphemus as his true kin, and Percy stays behind to fight beside Tyson rather than abandon him.

Percy and Tyson work together to hold Polyphemus off. Percy uses the sea to strike the Cyclops and argues that the Fleece should heal others instead of serving as bait for satyrs. When Polyphemus pretends to appeal to Tyson as a fellow Cyclops, Tyson hesitates and tries to make peace, but Polyphemus tricks him and smashes him with an olive tree. Percy counters by attacking Polyphemus's damaged eye, and Tyson recovers enough to tackle the giant.

With Polyphemus vulnerable, Percy has a chance to kill him, but Percy decides it is wrong and tells Tyson to flee instead. The two reach the water and swim for the Queen Anne's Revenge while Clarisse taunts Polyphemus from the deck. Because Clarisse keeps shouting, Polyphemus tracks her voice and hurls a boulder through the ship's hull, sinking it almost immediately and dragging Annabeth, Grover, and Clarisse into the deadly pull of the wreck.

Underwater, Percy realizes he may not be able to save everyone alone. Tyson speaks to Percy telepathically through the sea, revealing another sign of their shared connection to Poseidon, and together they call for Rainbow. Rainbow and two other hippocampi arrive, pull the sinking heroes from the wreckage, and carry them away from the island with the Fleece. Safe for the moment, Annabeth falls asleep, Percy covers her with the Fleece, and Percy gratefully rests as the group escapes.