Gaslight (1940)

In Victorian London, all the talk in one specific neighborhood is that someone has finally moved into 12 Pimlico Square, the house having sat empty for years as the previous owner, Alice Barlow, was murdered there, her valuable rubies thought to be stolen in the process, this information of which the new owners, newlyweds Paul and Bella Mallen, may or may not be aware. Bella's delicate constitution takes a turn for the worse after moving in: she keeps forgetting and misplacing things and thinking she hears noises coming from the closed-off upper floors of the house, and seeing the lights flicker when nobody else is in the house--flickers should only occur when other lights are turned on and off in the house in the gas to the lights being dispersed. Paul's love for her crosses that fine line into hate in dealing with Bella's worsening mental health; he isolates her in the house, not wanting her to cause public embarrassment. Paul's harsh treatment exacerbates the situation as Bella teeters on the brink of madness. However, B.G. Rough, the livery stable owner who was once a police constable who worked on the Barlow case, believes Paul Mallen not the person he says he is and is really someone indirectly associated to the Barlow case. With help from Bella's cousin Vincent Ullswater, who has always been at odds with Paul, who has refused to let him see Bella without his knowledge, Rough may uncover what is happening behind the locked doors of 12 Pimlico Square. Will he be too late to save Bella's sanity--or her life?