Miss Marple: The Body in the Library (1985)

A murder is announced in the Chipping Cleghorne Gazette to take place on October 5th, 7 PM at Little Paddocks cottage. The people living there, retired secretary Miss Blacklock, her companion Miss Bunner, Miss Blacklock's two distant cousins, Patrick and Julia and Mrs.Haymes, a gardener, have no idea what the ad is about. Several villagers arrive at the house under the false pretenses of "just walking by" or "Was in the neighborhood". At exactly 7 PM, the lights go out, and a man enters the room, and shines a flashlight in everyone's face. Then shots are heard. As the lights come back on, they find the man who entered the room has been shot. Miss Marple must unmask the killer but soon more murders turn up.