Manhattan Murder Mystery (1993) on Netflix

Middle aged New Yorkers Larry and Carol Lipton's marriage is in an unspoken rut. That rut is highlighted when they formally meet for the first time Paul and Lillian House, long time neighbors approaching their senior years who live on the same floor as them in their upscale Manhattan apartment building. The day after that meeting which included coffee in the Houses' apartment, Larry and Carol learn that Lillian died of coronary heart failure. Spurred on by having just watched Double Indemnity (1944), Carol, based largely on circumstantial evidence, believes that Paul may have murdered Lillian, as he is not bereft enough about her passing, especially as she had not mentioned any health problems in their detailed discussion during coffee the previous evening. Larry, a book editor, believes that Carol's imagination is working overtime, especially as she is currently unemployed, but whose most recent employment thought is to open a restaurant. Carol turns to their recently divorced friend Ted, a writer and a possible partner in the restaurant venture, to be Watson to her Sherlock Holmes in finding out conclusive evidence to her belief, no matter what it takes. Ted, who generally does have more of an adventurous spirit than Larry to match Carol in that respect, is a willing Watson. Larry believes Ted's willingness is because he is interested in Carol sexually. Larry, beyond wanting to set Ted up with Marcia Fox, one of his clients who seems to be interested in Larry himself, has to decide if he should get involved in Carol's investigative work if only to save their marriage. Things change when Carol discovers more and more evidence which points to Paul truly being a murderer, at which time the foursome of Carol, Ted, Larry and Marcia try to pull whatever references they can think of from books and movies to piece together the story and as such gather the necessary evidence, without really realizing that their lives may be in danger if Paul truly is a murderer and finds out they are after him.