When the demigods of Camp Half-Blood notice their powers start failing, they need answers. And Chiron isn't giving them any.

As it turns out, the gods are being held hostage by unseen forces. Four quests will be needed to save Zeus and Olympus, Hades in the Underworld, Artemis on her hunt, and Dionysus from Half-Blood. Otherwise, their greatest enemies will lay claim to the world.