I tend to think that any film titled Murder Mystery ought to offer a definitive take on the crime story. The 2019 movie of that name starring Jennifer Aniston certainly fails that test, but as light entertainment, it's perfectly acceptable. James Vanderbilt's script has a number of enjoyable moments, and the storyline - whilst hardly at the Christie level of ingenuity - is just about acceptable, as long as you don't think too much about the various plot holes. But then, it's not the sort of film you should think about too much.
Nick Spitz (Adam Sandler) is a not very competent New York cop married to a likeable hairdresser and mystery fan called Audrey (Aniston), who has always wanted to visit Europe. For their fifteenth anniversary, Nick finally gets round to booking a coach trip. On the plane, while Nick is asleep, Audrey is chatted up by wealthy Charles Cavendish (Luke Evans). On a whim, Cavendish invites the Spitzes to join him on his luxury yacht in the Med. I rather expected there to be a cunning explanation for this act of generosity - but there wasn't, an example of weak writing, I'm afraid.
The Spitzes find that they have joined a family celebration. Cavendish's elderly uncle Malcolm Quince (a great role for Terence Stamp) is about to marry Cavendish's former lover (Shiori Kutsuna) and the party also includes a variety of other people with good reason to wish Quince dead - at least before he can leave his fortune to his new wife. The cast is nicely varied, and includes Gemma Arterton and David Walliams.
Needless to say, Quince is murdered, and another death soon follows. When the yacht lands at Monte Carlo, the detective in charge concludes, on the basis of no evidence whatsoever, that the Spitzes are the culprits. This was the weakest part of the script, a contrivance that is quite inept. But compensation comes in the form of quite a few funny lines as the story wanders towards an unlikely conclusion.