It's usually not too hard to discern a film that was adapted from a stage play. There's an economy of cast and settings that indicates a necessity for limiting each. Alfred Hitchcock's "Dial M for Murder" has both: There are only five significant roles, and almost the entirety of the action takes place inside a single apartment, and nearly all of that in one room.
Dial M for Murder (1954)
Dial M for Murder (1954)
Dial M for Murder (1954)
It's usually not too hard to discern a film that was adapted from a stage play. There's an economy of cast and settings that indicates a necessity for limiting each. Alfred Hitchcock's "Dial M for Murder" has both: There are only five significant roles, and almost the entirety of the action takes place inside a single apartment, and nearly all of that in one room.