The House of Hades is the fourth of five books in the Heroes of Olympus series, which follows seven Greek and Roman demigods on a quest to prevent the rise of the earth goddess Gaea, who is bent on destroying the world.

The House of Hades was written by Rick Riordan, a New York Times bestselling author who explores Roman and Greek Mythology in these two series. Riordan is the publisher of an imprint with Disney Hyperion that seeks to publish works of fiction that explore world cultures and mythologies. Riordan has a standalone Percy Jackson book forthcoming in 2023: Percy Jackson and the Olympians: Chalice of the Gods. Other works by this author include The Lightning Thief, The Sea of Monsters, and The Battle of the Labyrinth.

This guide is based on the 2019 Disney Hyperion paperback edition.

Plot Summary

The House of Hades is told from an omniscient third-person point of view that switches between the seven members of the quest: Percy Jackson, Annabeth Chase, Hazel Levesque, Frank Zhang, Leo Valdez, Jason Grace, and Piper McLean. This is the only book where all seven protagonists of the Heroes of Olympus series have a featured point of view.

The House of Hades begins directly after the events of Mark of Athena. Protagonists Hazel, Frank, Jason, Piper, Leo, and Coach Hedge fly the Argo II (a flying Greek ship) across Italy to the Doors of Death in the House of Hades, where they plan to stop the monsters and rescue Percy and Annabeth, who have fallen into Tartarus (the underworld). The chapters alternate between the Argo II quest members and Percy and Annabeth and their adventures in Tartarus.

Percy and Annabeth land in the River Cocytus in Tartarus and manage to survive the deadly Tartarus by drinking from the River Phlegethon, the River of Pain, which heals mortals. When they are cornered by empousai monsters on their way to the Doors of Death, they are rescued by Bob, the former Titan Iapetus whose memory Percy wiped in the River Lethe and left as a janitor to Hades. Bob guides them to a temple to Hermes where Annabeth sends a message to Reyna through the Oracle of Delphi, Rachel. Percy and Annabeth are assaulted by arai, curse monsters who tell Bob that Percy wiped his memory. Betrayed, Bob abandons them until Percy whispers an apology while dying. Bob takes them to the house of the giant Damasen, who heals the curses on Percy but refuses to come with them. Bob leads them to the goddess of misery, Akhlys, who gives them the Death Mist to prevent monsters from seeing them. Percy and Annabeth go to the Doors of Death where the god Tartarus appears in his physical form to kill them, but Bob and Damasen sacrifice themselves while Percy and Annabeth cut the chains of the Doors of Death and escape to the mortal world. 

While Percy and Annabeth are journeying through Tartarus, the Argo II crew fights to meet them. Hazel meets Hecate, goddess of magic and crossroads, who shows them a safe passage to the House of Hades and tells Hazel she must learn to use the Mist, the Greek form of magic, to defeat her foe in the House of Hades. Leo guides the Argo II to Bologna where two thieving brothers, known as the Kerkopes, attack them. Leo and Jason chase them through the streets, and Leo recovers their stuff: an astrolabe of Odysseus’s, and a book for the farming god Triptolemus in Venice. Leo sends the brothers to attack the Roman demigods marching on Camp Half-Blood and delay the war.

In Venice, Frank proves himself worthy by killing the entire population of cow monsters and earns the blessing of his father Mars. Frank bargains with Triptolemus to save Hazel’s and Nico’s lives and obtains barley, the secret to surviving the poison in the House of Hades. After Venice, Jason has a dream about Reyna leaving the Roman demigods to bring the Athena Parthenos back to Camp Half-Blood and prevent war. Jason leads the crew to Diocletian’s Palace where he and Nico face Eros, the god of love. Nico must admit that he loves Percy to get the scepter. Jason accepts him, but Nico doesn’t want to tell the others.

After obtaining the scepter, the crew is attacked by Khione the snow goddess, who sends Leo to Calypso’s Island and freezes everyone but Piper because she thinks the daughter of Aphrodite is useless. Piper uses love and charmspeak to make Festus come alive, defeat Khione, and unfreeze her friends. Khione releases a wind bomb that blows them to Africa where the lord of the South Winds makes Jason choose to be Greek or Roman. Jason chooses Greek and gets wind horses to take them to Malta where they meet Leo, who had been stranded with Calypso. After Calypso falls in love with Leo, he leaves but vows to return.

The Argo II travels to the House of Hades where Jason, Nico, Frank, and Piper face an army of monsters while Leo and Hazel fight the sorceress Pasiphaë and the giant Clytius at the Doors of Death. Nico summons ghostly Roman legions with Diocletian’s scepter, and Frank controls them after Jason resigns his post as praetor and promotes Frank. After defeating the monsters, Frank uses his power as a child of Mars to summon defeated ghosts to lead them to Hazel and Leo. Hazel manipulates the Mist to defeat the sorceress Pasiphaë and her Labyrinth. Hecate arrives to help Hazel defeat Clytius, who guards the Doors of Death. Hazel cuts the chains of the Doors of Death and fights Clytius until Jason, Nico, Frank, and Piper arrive. Hecate kills Clytius with their help. Hecate tells them to go to Athens to fight the Giants and prevent Gaea from rising. The crew emerges from the House of Hades to find Reyna and Coach Hedge waiting. Nico agrees to shadow-travel Reyna, Coach Hedge, and the Athena Parthenos to Camp Half-Blood to prevent the demigod war. Percy, Annabeth, Jason, Piper, Frank, Hazel, and Leo take the Argo II to Athens to fight the giants and stop Gaea.