Le Train de 16 h 50

The way the mystery unfolds is so clever, but I didn't see the final twist coming. Did others figure it out earlier?

The confined space of the train feels perfect for a whodunit, but I'm curious if that was a deliberate choice or just a happy coincidence.

The train as a backdrop adds a unique pressure cooker environment, but I wonder if the setting was based on real experiences or purely fictional.