A middle-aged couple suspects foul play when their neighbor's wife suddenly drops dead.
Larry and Carol are fairly normal New Yorkers who have sent their son off to college. They meet an elderly couple down the hall and later in the week find that the wife has suddenly died. Carol becomes suspicious of Paul who seems to be too cheerful and too ready to move on. She begins her investigation. Larry insists she is becoming too fixated on their neighbor as all of the irregularities seem to have simple non-homicidal explanations. Ted, a recently divorced friend helps her investigation and Larry begins to become jealous of their relationship and agrees to help her.
Woody Allen and Marshall Brickman planned to make Annie Hall (1977) a murder mystery, but cut that subplot out and used it for this movie. They had been working on a script about two New Yorkers who stumble upon trying to solve a murder, when Woody got stuck. While blocked, he noticed a book on Russian history at his home. As the deadline was fast approaching for delivery of a contracted screenplay, Allen got inspired and decided to spoof the entire genre of novels based on Russian history, and this became Love and Death (1975). He put the Marshall Brickman collaboration mystery script on the back-burner. That script eventually became the genesis for this film.
Diane Keaton replaced Mia Farrow. Woody Allen had written the lead female role for Farrow, but Keaton got the part following the breakup of the pair's personal relationship. There is a rumor that, despite their very public feuding between her and Allen, Farrow still showed up for a costume fitting, and needed to be informed that she was no longer in the movie.
This is the fourth and final writing collaboration between Woody Allen and Marshall Brickman. The previous one was the similarly titled Manhattan (1979).
Anjelica Huston said that the set was "oddly free of anxiety, introspection and pain" and attributed this largely due to the presence of Diane Keaton. Huston added: "On this movie, he [Woody Allen] showed up in the hair and makeup trailer to tease Diane about her hair and her big photography books, all diligently marked with yellow stick-'em paper. Around Diane, he was open and accessible".