Heroes of Olympus : The House of Hades

The Heroes of Olympus series narrates the adventures of seven demigods. These young adults are children of Roman and Greek Gods and mortals, and each of them have special powers. The series enumerates the quests these seven heroes undertake in order to save earth from Gaia, the main villain of the series.

At the end of the third book of The Heroes of Olympus series, The Mark of Athena, Percy and Annabeth, two of the seven demigods are falling towards Tartarus, the underworld prison that is guarded by the Doors of Death.

In the beginning of The Heroes of Olympus: The House of Hades, Percy and Annabeth are in Tartarus. They undertake a perilous journey, fighting a number of demons and monsters to reach the Doors of Death from inside Tartarus. Meanwhile, in the world of mortals, the other demigods are on a quest themselves, to find and save Percy and Annabeth.

The impending doom of the rise of Gaea and danger, for all mortals on earth is approaching. The seven demigods must unite to save the people of earth. They must seal the doors of the underworld before the demons escape. However, Percy and Annabeth will be lost forever in Tartarus if they cannot escape before the doors of the underworld are sealed.

Like the rest of the series, The Heroes of Olympus: The House of Hades is extremely fast paced and difficult to put down.