Spurred on by the success of "The Amityville Horror" and other similarly creepy tales that were at cinema's in the early 80's. Distributors 20th Century Fox got the idea of adapting the novel by Frank DeFelitta, which is partly based on a supposedly true story.
The plot centres around working single-mother Carla Moran (Barbara Hershey), who lives with her teenage son and two younger kids in their suburban Californian house. However, her life is turned upside down one evening when she receives a visit from a rather unfriendly supernatural being, who is definitely NOT "looking for the light", as she finds herself being forced down onto the bed and apparently raped by an unseen force.
Her friends think she's barmy, and book her in to see a psychologist at the local university. The resident Doctor, Phil Sneiderman (played by notorious screen baddie Ron Silver), seems to think she's been having some sort of fit, and disputes her claims about being attacked by a paranormal pervert, despite the fact this "entity" also managed to throw her teenage son across the room and break his arm during one of the attacks.
The attacks continue, but fortunately the paranormal research team at the university do believe her story, and so begin to investigate. Much to the annoyance of Dr Sneiderman, who thinks she's delusional, which leads to an interesting final confrontation when they try to trap the being in a university lab experiment.
Whilst not quite as good as Poltergeist, the film is certainly much better than Amityville Horror and is definitely worth watching. The special effects are certainly very good, but then they were done by Stan Winston's effects shop. How much of this film is actually true is anybody's guess, but then "The Exorcist" was supposedly based on a true story right? (Yeah, right!) But in any case, the film is certainly worth seeking out