On a moon-lit night, Diké, heir to the Kingdom and leader of the terrifying warrior cult, the Ogwumii, falls asleep inside his bedroom. He wakes up to find himself trapped within the secret shrine of the village deity, a dark cave forbidden to all save the powerful witchdoctors. Overnight, the mighty warrior-prince becomes an Osu-- an untouchable and outcast. In disgraced exile in the forbidden shrine, his sole companion is the raging ghost of a murdered slave girl, wrongly sacrificed to the gods on the false prophecy of a lecherous witchdoctor. To break the Osu curse, Diké must find the traitors who orchestrated his downfall and embark on a terrifying journey to the ancestors' realm, a deadly quest that could end his life or return him to full citizenship and glory.