After the unexplained disappearance of both Aphrodite and Hephaestus, the remaining gods of Olympus convene an emergency council to tackle the problem. Rejecting Hercules's outlandish idea that Hades might have returned, they dismis- sively send the demigod on another divine errand this time to the city of Thessaly, which is under attack from an army of centaurs.

As Hercules and Galatea take on the hooved besiegers, Meg and Phil search for the source of their hostility- only to find that their main suspect has become the latest victim of the ongoing rash of supernatural vanishings!