Perhaps because it is based on a true story,' this horror film is afflicted with a vagueness of definition: the invisible rapist who bedevils the young single mother (Barbara Hershey) is not a house-haunter as in Poltergeist nor a body-possessor as in The Exorcist. What, then, is he, and where in screen history do we look for his like? The vagueness alone need not make us impatient; it perhaps even enhances the air of reality. We soon become impatient, however, with psychiatric patter about childhood trauma, sexual hysteria, mass delusion, and so forth, when we have seen for ourselves what the thing can do: doors shutting by themselves, lamps turning on, blue lightning bolts crackling from the fingertips of the heroine's teenage son. The insistent, earnest psychiatrist (Ron Silver) is much better engaged when he must compete with a couple of grad-studenty parapsychologists. The testy verbal exchanges between the psychological mainstreamer and these two fringe-dwellers are an enjoyable standoff; the visual evidence, which piles high in the rousing but not totally satisfying climax, proves nothing, of course, except the continued vitality of the horror genre. The slight dissatisfaction at that point may again have to do with the "based on a true story." Written by Frank DeFelitta; directed by Sidney Furie. (1983) — Duncan Shepherd