In 1992, a group of young Anarchists seeking to preserve local wildlife are brutally murdered. The killer is later found collapsed by a river due to wounds he had sustained while attempting to kill a lone surviving anarchist. The movie flashes forward 15 years to 2007, as successful crime novelist Susan moves into a nearby house with her husband David, who purchased it in hopes of helping her with her writing. Susan is quickly made uneasy as she witnesses the house's gamekeeper, Peck, having enthusiastic sex in the woods and later exposing himself to her. She also begins to witness strange visions in the house, all surrounding bloody bodies, the killer from earlier in the film, and people who appear one moment and disappear the next. It is later revealed that Susan had previously suffered a mental breakdown due to seeing and hearing things that were never there, which was part of the reason for the house's purchase. After David leaves for a "business trip", Susan is drugged and taken advantage of sexually by Peck. The next day, Susan confides in a local priest about her past mental illnesses and her fears of her new home. The priest has a psychic examine the house, only for him to declare that there are no presences currently in the house. Immediately after they are escorted outside by her husband, Susan witnesses a series of brutal murders involving all of the people she had earlier seen in her visions. The vision end up destroying what little sanity Susan has left, resulting in her accidentally killing Peck as he was checking up on her. Upon discovering what she has done, Susan is sent to a mental institution. The movie then shows that Susan had been channeling her visions into her latest book, which has become an instant bestseller. David is shown receiving money for the book and it is implied that he had married her only for her money, and that Peck's actions were done in an attempt to get blackmail material for a divorce. David then goes back to the house one last time to finalize the sale to a new owner, where we are an shown all of the people Susan had seen during her visions. He is then gruesomely murdered by the killer Susan had been seeing all along, revealing that her visions had never been due to insanity, and were predictions of the future murders that would happen in the house.
Psychosis has received mostly negative reviews from critics, with Scott Weinberg of Fearnet recommending the film as a "sleeping aid" to viewers and HorrorNews.net saying that the film was "unoriginal, boring, and confusing as hell at times". Reelfilm reviews wrote that while the film has a "reasonably competent sense of style", ultimately it was "impossible to label Psychosis as anything more than a fleetingly captivating yet thunderously misguided piece of work." Fangoria also panned the film, stating that "PSYCHOSIS is a terribly boring film with an ending that doesn’t reward viewers for undertaking it’s gruelingly sluggish pace." Eye For Film positively reviewed the film, calling Psychosis "a rarr stately, old-fashioned feeling film". Dread Central wrote that "Psychosis is definitely worthy of a watch, and in the end it is only its pacing issues that keep it from rising above a good level into greatness."
