The fourth book in the bestselling Heroes of Olympus series by Rick Riordan, now with fresh and exciting new cover art by graphic novelist Nilah Magruder.
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