Psychosis (2010)

In 1992, a group of young anarchists, seeking to preserve local wildlife, are brutally murdered. The killer is later found by the river, having collapsed from wounds he sustained while trying to kill a lone surviving anarchist.

The movie flashes forward 15 years to 2007, as a 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 after she witnesses the house's gamekeeper, Peck, having enthusiastic sex in the woods. He later exposes himself to her. Susan begins to witness strange visions in the house, all surrounding bloody bodies: the killer seen at the beginning of the film and other people who appear and disappear. It is later revealed that Susan had previously suffered a mental breakdown due to seeing and hearing the things that were not actually there, which was another reason for David purchasing the house.

After David leaves for a "business trip" (quickly revealed to be an excuse to indulge in affairs), Susan is drugged and raped 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 arranges for a psychic to examine the house, only for him to declare that supernatural entities are present in the house.

Immediately after they are escorted outside by David, Susan witnesses a series of brutal murders involving everyone seen previously in her visions. The vision ends 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 goes back to the house one last time to finalize the sale to a new owner, where all the people Susan had seen during her visions are then shown. He is then gruesomely murdered by the killer Susan had been seeing all along (who had survived, been incarcerated, and escaped), revealing that her visions had never been due to insanity, and were predictions of the future murders that would happen in the house.