The Titan's Curse is the third installment in the series. It was released on May 11, 2007.
On a mission to rescue half-bloods Bianca and Nico di Angelo, Percy, Annabeth, Thalia and Grover are attacked by a manticore and rescued by the goddess Artemis and her Hunters. However, Annabeth falls off a cliff whilst trying to fight the manticore and is said to be captured. Later, Artemis is captured by Luke's army while on the hunt for the Ophiotaurus, a cow-serpent monster that was foretold to bring the downfall of Olympus when its entrails are sacrificed to a fire. Her lieutenant Zoe Nightshade, daughter of Atlas, leads Bianca, Thalia and Grover on a quest to save her. Percy, who was not invited to join the party, follows them on behalf of Nico Di Angelo, promising that he will do his best to protect his sister, Bianca. The others eventually find Percy, and he joins their groupto find annabeth. They become the prey of skeletons, who chase them across the country. Bianca is able to kill one, which leaves the others mystified. Bianca later dies as they make their way across a godly junkyard. They find Annabeth with Luke and Artemis, who is holding up the sky. Percy then takes it from Artemis and they trick Atlas into his original position under the sky. Thalia replaces Zoe, who dies, as Artemis' lieutenant. Thalia's induction as a lieutenant of Artemis ensures that she will become immortal, never aging to 16, thus escaping the Great Prophecy and leaving Percy to fulfill it. They return to camp and Percy informs Nico about Bianca's death during the journey. Nico blames Percy for failing to protect her and runs away, only after killing skeletons that invade the camp, so that Percy realizes that Hades is Nico's father.