The House of Hades is a fantasy-adventure novel written by American author Rick Riordan, based on Greek and Roman mythology.

The story follows the Greek demigods Annabeth Chase, Leo Valdez, Piper McLean, Nico di Angelo, and Percy Jackson, and the Roman demigods Jason Grace, Hazel Levesque, and Frank Zhang on their quest to close the Doors of Death, stop the Giants from raising Gaea, and prevent war between Camp Jupiter and Camp Half-Blood.

During the first week of its release, The House of Hades sold about 350,000 copies, reaching the top of the bestseller lists of The New York Times, USA Today, The Globe and Mail and The Wall Street Journal.

After Annabeth Chase and Percy Jackson fall into Tartarus at the end of The Mark of Athena, the other five demigods of the "Prophecy of Seven" (Frank Zhang, Hazel Levesque, Jason Grace, Leo Valdez and Piper McLean), aided by Nico di Angelo and Coach Hedge, prepare to go to Greece to find and close the Doors of Death from the mortal world in order to prevent the monsters of Gaea's army from continuously resurrecting.

In Bologna, the Argo II is raided by the Kerkopes; Leo goes after them to retrieve his stolen Archimedes's sphere, and takes an agricultural book belonging to Triptolemus and an astrolabe made by Odysseus as recompense.

During a later encounter with the bandit Sciron and after a meeting with the goddess Hecate, Hazel successfully learns to manipulate the Mist, a power that alters other people's reality layers by deceiving them.

While Leo is detained, the rest of the crew meets with Notus, who helps Jason to realize that he has chosen to be a Greek rather than a Roman demigod, settling an internal conflict within himself.

[1] The House of Hades was announced by Rick Riordan through his website on October 20, 2012, two weeks after the launching of The Mark of Athena, the third book in The Heroes of Olympus series.

"[4] In an interview with US News, Riordan said that to write the book, he used his experience of having traveled to the Mediterranean with his family as part of a Disney-Hyperion promotion for the end of the Percy Jackson & the Olympians.

Many of the tourist destinations he visited were included in the series, but because of the conflicting portrayals of Tartarus in literature, the author said that he appealed to his imagination to write the scenes of the underworld.

A journalist of The Guardian praised Riordan's ability to handle the multiple-perspectives format smoothly and referred to his "subtle and effective" treatment of "more mature themes," including the revelation of Nico's sexual identity.

"[18] Karen Rought of Hypable considered The House of Hades as "one of the most gripping tales Riordan has written in his Percy Jackson world."

"[19] Kirkus's analysis highlighted the portrayal of Tartarus as a "hellish, monster-infested landscape," as well as the development of the characters, making moments of jokes rarer.