When a witch doctor appears on the Marquis de Casalduero`s doorstep prophesizing a plague of rabies in their Colombian seaport, he dismisses her claims - until he hears that his young daughter, Sierva Maria, was one of four people bitten by a rabid dog, and the only one to survive.
Sierva Maria appears completely unscathed - but as rumours of the plague spread, the Marquis and his wife wonder at her continuing good health. In a town consumed by superstition, it`s not long before they, and everyone else, put her survival down to a demonic possession and begin to see her supernatural powers as the cause of the town`s woes. Only the young priest charged with exorcizing the evil spirit recognizes the girl`s sanity, but can he convince the town that it`s not her that needs healing?