House of Hades, The-Heroes of Olympus, The, Book Four: The House of Hades

At the conclusion of The Mark of Athena, Annabeth and Percy tumble into a pit leading straight to the Underworld. The other five demigods have to put aside their grief and follow Percy's instructions to find the mortal side of the Doors of Death. If they can fight their way through Gaea's forces, and Percy and Annabeth can survive the House of Hades, then the Seven will be able to seal the Doors from both sides and prevent the giants from raising Gaea. But, Leo wonders, if the Doors are sealed, how will Percy and Annabeth be able to escape? They have no choice. If the demigods don't succeed, Gaea's armies will never die. They have no time. In about a month, the Romans will march on Camp Half-Blood. The stakes are higher than ever in this adventure that dives into the depths of Tartarus.This paperback edition will include a never-before-seen short story, "The Crown of Ptolemy," in which Percy and Annabeth fight alongside Carter and Sadie Kane, and more bonus content!

• The Heroes of Olympus, Book Five The Blood of Olympus
• Heroes of Olympus, The Book Three The Mark of Athena (The Heroes of Olympus)
• The Son of Neptune (Heroes of Olympus, Book 2)
• The Lost Hero (Heroes of Olympus, Book 1)
• The Hidden Oracle (Trials of Apollo, The Book One)
• The Heroes of Olympus Paperback 3-Book Boxed Set
• The Lost Hero (Heroes of Olympus, Book 1)
• The Last Olympian (Percy Jackson and the Olympians, Book 5)
• The Battle of the Labyrinth (Percy Jackson and the Olympians, Book 4)
• The Dark Prophecy (The Trials of Apollo, Book Two)