A young man begins acting in violent manners and, in turn, comes under the care of a psychologist and the suspicion of the cops. His mothering sister tries to find an explanation for his behavior but isn't quite willing to except the one she is given, that her brother has been possessed by the spirit of a serial killer.
An extremely tense and thrilling film. It is well-directed and the actors give a very believable performance. Well worth watching.
On a technical note: The film was originally shot in 4:3 and then converted to widescreen, for it's theatrical release, by removing top and bottom of the frame. This meant that the director didn't need to worry about boom-mics being in shot, because he knew they would be removed in the widescreen version. The same also applied to David Elliott's penis during the beach-house sequence, with the widescreen version being cropped just above the groin.
The VHS release was of the orignal 4:3 version, as it was originally shot. The DVD release is of the widescreen theatrical version.