Percy takes command of the Queen Anne’s Revenge and discovers he has a natural gift for sailing, but his relief is mixed with guilt about Tyson, worry for Grover, and lingering fear from being turned into a guinea pig by Circe. As he and Annabeth sail through dangerous waters, she becomes seasick, warns him away from one of Hephaestus’s volcanic forges, and then tells Percy why she hates Cyclopes. Years earlier, a Cyclops in Brooklyn used stolen voices to trap Annabeth, Luke, Thalia, and Grover, and Annabeth believes that delay allowed the monsters who later killed Thalia to catch up.

When Percy finally sleeps, he dreams he is back in Luke’s stateroom on the Princess Andromeda, facing Kronos’s glowing sarcophagus. A punk-looking girl with a powerful shield approaches the coffin and opens it despite Percy’s warning, only to be overwhelmed by a burst of golden light as Kronos laughs. Percy wakes when Annabeth alerts him that they are nearing the island of the Sirens.

Annabeth insists on hearing the Sirens because their song reveals a listener’s deepest desires and can grant wisdom if the listener survives. Percy reluctantly helps by tying her to the mast while he seals his own ears with wax and pilots the ship. As they near the island’s deadly rocks and wreckage, Annabeth becomes desperate to reach the song. Percy resists freeing her, but he makes a critical mistake by leaving her knife within reach, and she cuts herself loose and swims toward the shore.

Percy leaps into the water and chases her through a deadly maze of jagged rocks, mines, and wreckage. Inside the bay, he sees the Sirens as monstrous bird-women whose faces shift into the people he most wants to see. When Percy grabs Annabeth, he also sees the vision they are offering her: her parents reunited, Luke restored, and a rebuilt, perfect Manhattan designed by Annabeth herself. Realizing the song feeds her desire to remake the world, Percy drags her underwater, creates an air bubble to keep her alive, and breaks the Sirens’ spell.

Back aboard the ship, Annabeth admits the Sirens revealed her fatal flaw: hubris, the pride that makes her believe she could rebuild the world better than anyone else, even the gods. Percy understands how dangerous that temptation is, especially because Luke’s ideas appeal to the same impulse. Still unsettled by his dream of Kronos, Percy soon sees the saddle-shaped island from his visions ahead. Using his new nautical instincts, he confirms that he and Annabeth have reached the home of the Cyclops.