How was the first not a whodunnit? There are plenty of whodunnits with twists like that.
It’s not a whodunit because the movie begins with you “knowing” whodunit, and then ends with the twist being actually “no one” dunit. Never at any point in the movie does the viewer wonder “whodunit”, which is literally the only requisite for a movie to be classified as a whodunit.
Two bonus points can be awarded for how bad it is as well. The first being that the answer to who the real villain is, is the only character in the movie who obviously presents from the start as the villain. The whole twist is “You thought the cartoonishly villainous person was an obvious red herring and that we have a much more clever villain in store, but nope. They just actually are the villain”. The second being that the ending monologue posits that Martha is not a killer because “She’s too good of a nurse”, when in reality she’s a horrible nurse with zero attention to detail and her horrible incompetence is the only reason she isn’t the killer.
I can’t think of any other whodunits where the twist is “Like a whodunit, but you aren’t even aware there is a mystery until after it’s solved, and the secret villain of the movie turned out to just be the person we introduced to you as the villain in the first act.”
I’m sorry to tell you this but:
https://www.merriam-webster.com/dictionary/whodunit
The mystery in question doesn’t necessarily need to be who is the murderer, as in this case it is largely “who is blackmailing the nurse?” Even “how does Blanc puzzle it out” qualifies it as a detective story itself.
It’s fair if you want a stricter definition but you are going to run into pushback on a personal definition.
I’m sorry to burst your bubble but:
https://dictionary.cambridge.org/us/dictionary/english/whodunit
https://www.dictionary.com/browse/whodunit
The mystery in question specifically refers to a crime, usually a murder specifically and who committed it. Hence the “who” in “whodunit”. Thats why they don’t call it a “Whoisit” or “howdoeshe”
