The residents of Chipping Cleghorn are astonished to read an advert in the local newspaper that a murder will take place the following Friday at 7:30 p.m. at Little Paddocks, the home of Letitia Blacklock. A group gathers and at that precise moment, the lights go out and a young hotel employee, Rudi Schertz, is shot. The police assume he had placed the ad and planned it as a robbery, but for Miss Marple it's not that obvious. She believes that the killer was likely one of the people in the room.