The boys gain an unexpected addition to their workforce with the arrival of Pythagoras's feisty younger brother, Arcas. Charged with escorting a valuable cargo across the desert, the gang travels into the unknown with a ramshackle caravan of strangers.

It is not long before their journey takes a decidedly spooky turn; after spending a night in a temple dedicated to the Furies, it soon becomes clear that one amongst their number has something to hide. As danger closes in and a dark secret is exposed, our heroes are forced to confront some uncomfortable truths as they fight for their lives under the desert sun.

After the tragic events surrounding Medusa's disappearance, the boys pay a visit to the inventor Daedalus, whose genius offers hope of a cure. But, unwilling to wait for answers, Hercules acts on information from the unscrupulous Crios and sets off in search of his lost love. His decision soon sees the boys literally running for their lives as they become the prey in a brutal manhunt. With hopes of an escape fading fast, their courage is tested to its limit, until a lifeline comes from an unexpected source.