"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 Percys instructions to find the mortal side of the Doors of Death. If they can fight their way through the Gaeas 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...

"Percy Jackson isn't expecting freshman orientation to be any fun. But when a mysterious mortal acquaintance appears on campus, followed by demon cheerleaders, things quickly move from bad to diabolical. In this latest installment of the blockbuster series, time is running out as war between the Olympians and the evil Titan lord Kronos draws near. Even the safe haven of Camp Half-Blood grows more vulnerable by the minute as Kronos's army prepares...

Demigod Percy Jackson, still with no memory, and his new friends from Camp Jupiter, Hazel and Frank, go on a quest to free Death, but their bigger task is to unite the Greek and Roman camps so that the Prophecy of Seven can be fulfilled.