Percy Jackson and the Sword of Hades recap

In this short adventure set during the war against the Titans, Persephone secretly summons three demigods, Percy Jackson, Thalia, and Nico di Angelo, to the Underworld. A powerful new sword of Stygian iron, forged for Hades and able to command the dead, has been stolen, and it must be recovered before it strengthens the enemy. The trio pursue the thief and clash with the demigod Ethan Nakamura and the ancient Titan Iapetus, who has taken the blade. In a desperate fight Percy hurls Iapetus into the River Lethe, the river of forgetfulness, which wipes away the Titan's memory and his hatred. Reborn blank and gentle, the confused Titan is given the harmless name Bob. The demigods retrieve Hades' sword and return it, denying it to the Titan army. Nico remains in the Underworld with his father, and Percy leaves with the war against the Titans still ahead of him.

In the first four books of the series, Percy Jackson learns he is a demigod son of Poseidon and finds a home at Camp Half-Blood, the sanctuary for children of the Greek gods. Over successive quests he recovers Zeus's stolen master lightning bolt, retrieves the Golden Fleece to heal the camp's borders, which also restores his friend Thalia, daughter of Zeus, to life, and helps rescue the goddess Artemis and his friend Annabeth, after which Thalia joins the immortal Hunters of Artemis. Along the way the lonely, powerful Nico di Angelo is revealed to be a son of Hades. Beneath all these adventures, the exiled Titan lord Kronos is gathering strength and followers to overthrow the gods, working through the embittered demigod Luke Castellan, and by now Kronos has taken physical form. With open war between the Titans and Olympus drawing near, both sides scramble for any advantage, and the demigods know a decisive conflict is coming.

With the war against the Titans looming, Persephone, the queen of the Underworld, secretly calls three demigods down to the land of the dead: Percy Jackson, the Huntress Thalia, and Nico di Angelo, son of Hades. A powerful new sword has been forged for Hades from Stygian iron, a blade said to be able to command the souls of the dead, and it has been stolen. Persephone wants the three heroes to recover it quietly and quickly, before it can be turned against Olympus in the coming battle and before the theft causes more trouble. Reluctant allies with very different tempers, the trio set out through the dangers of the Underworld to track down the missing weapon and whoever took it.

The three demigods recover the stolen Stygian iron sword forged for Hades, keeping it out of the Titan army's hands as the great war looms. The turning point comes when Percy plunges the Titan Iapetus into the River Lethe; stripped of every memory, the Titan loses his malice along with his past, and the newly harmless being is nicknamed Bob. The thief Ethan Nakamura's scheme fails, and the weapon is returned to Hades. Nico di Angelo stays behind in the Underworld with his father, still finding his place there, while Percy and Thalia return to the world above. The victory is small against the scale of the coming conflict, but it denies the enemy a dangerous prize and leaves an unexpected, gentle Titan wandering the land of the dead.