Jason, Piper, and Leo, three students from a school for "bad kids," find themselves at Camp Half-Blood, where they learn that they are demigods and begin a quest to free Hera, who has been imprisoned by Mother Earth herself.

At the conclusion of The Mark of Athena, Annabeth and Percy tumble into a pit leading stragith 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 Door of Death. If they can fight their way through the 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...

Eleven-year-old Demon had never met his father, the god Pan, until the day he was whisked away to the stables of Olympus and charged with looking after all of the mythical creatures there, a task which is complicated by the tempestuous gods and goddesses and Heracles, who keeps killing the immortal beasts.