16-year-old Margaret Larkin is found murdered: tied to her own bicycle and drown in the Styx River where her parents died in an accident ten years before. Her murderer, wealthy and insane Nathan Redfield, believes he got away with the crime. But soon he begins to see not only the ghost of Margaret, but other watery spirits that pursue him. The fever of a guilty conscience? Encroaching insanity? Or has Nathan inadvertently awaken the sinister and vengeful spirit of the river itself?