Taut body countdown thriller that inexcusably cheats the ending

Rating: 5/10 (12 August 2018)

There's a lot I can't discuss without revealing spoilers, so I'll say this:
This movie begins as a well-produced, taut, whodunit murder thriller with top, popular, well-known actors way better than the movie deserved, with the familiar body count countdown, as a fixed group of people in an isolated space, slowly die one by one, while we try to figure out who the killer or killers are.
Meanwhile, a separate plot hints that something else may be going on.
Then the reveal comes at the end, and it cheats the whole thing saying "yes, the plot events don't make sense, but it's not supposed to, and this is why."
Remember how let down you were when that emotionally draining dramatic plot ended up being a dream?