Allen and Keaton meet a tedious older couple, Jerry Adler and Lynn Cohen. Keaton is first shocked, then intrigued, when Cohen later "dies" from a sudden heart attack. Adler's explanations become increasingly suspicious, and soon Allen, Keaton, Alda and Huston are all caught up in proving that Adler is guilty of murder, getting Allen and Keaton into Rear Window-style hot water.
How others will see it. Manhattan Murder Mystery was hardly the mainstream commercial success of certain prior Woody Allen films, but that ship had long departed by 1993. The movie made money, and it did so despite the relationship scandals that dogged Allen at the time (Allen married the adopted daughter of his lover Mia Farrow, who also alleged child molestation that few actually believed at the time).
The film received positive reviews from critics, and garnered consequential nominations from the Golden Globes, BAFTA, and the César Awards. Today at imdb.com, the movie has a fairly high 7.4 user rating, which rises to 7.6 among women over 45. The 32K user vote total is reasonable, though much less than the 228K user votes for Annie Hall, the commercial high-water mark of his career.
The user reviews are highly favorable. The chemistry between Allen and Keaton is praised, the dialogue is regarded as witty, and the film's breezy quality (despite its two murders and one kidnapping) is also applauded.
How I felt about it. I don't believe it is legitimate to criticize this (or any other) Woody Allen movie because of Mia Farrow's allegations against him. A movie has to stand on its own, independent of what Allen may (or may not) have done in his personal life.
That said, there was much about Manhattan Murder Mystery that I found mildly annoying: Keaton's bemused attitude toward Alda's all-too-obvious infatuation with her; Huston's romantic interest in married nebbish Allen; Keaton's sometime jealousy of the nebbish Allen; and Adler's casting against type as a ruthless murderer and kidnapper. This guy concocted a scheme to pass off a dead woman as his wife, then murdered his actual wife to run off with his mistress?
The actions of Keaton, in particular, seem unlikely. She is breaking into apartments, hiding under beds, skulking about a junkyard, and spending hours in a car with a panting would-be paramour to prove her remote and implausible hypothesis concerning Adler?
I believe the real reason for the popularity of the movie is the audience's admiration for the cast, whom they have known for decades and are like old friends. Indeed, Keaton was Allen's good-luck charm, and provides the best reason for anyone to sit through this movie.