"Stream" is the code name of an experiment that took place in the middle of nowhere, but which was cancelled before it could be completed. Bruce and Eve, both mentally deranged, participated in this experiment until the day Eve was murdered. Upon being released from the mental hospital, Bruce returns to the place where the experiment took place, bringing along Linda, a young hitchhiker he has kidnapped. Bruce seeks to replace his beloved Eve with Linda, but she refuses to be a part of his sick game. When two young women rafters show up, Linda seizes the opportunity and tries to escape. However, Bruce hits her and throws her, seriously hurt, into the river...