SOMEONE BEHIND THE DOOR (1971)

[The Burgomaster]

Anthony Perkins plays a doctor who wants to kill the lover of his cheating wife (Jill Ireland).  He concocts a plot to convince an amnesia patient (Charles Bronson, in a very offbeat role), that the doctor's wife is really the amnesia patient's wife.  Confused, jealous, and angry, Bronson is drawn into the murderous plot. 

This isn't a great movie, and I wish it had a better ending, but it's pretty good and it's nice to see Bronson in a role other than a vigilante or a cop.  Most of the movie takes place in Perkins' home, so it could easily be converted into a stage play.  You might want to give this one a try. 

[zombie no.one]

(Charles Bronson, in a very offbeat role)

can't be that offbeat, looks like he still manages to wave guns around, as per...

never heard of this film

[The Burgomaster]

never heard of this film

It's actually a French film (and the original title is French), but all the actors speak English . . . there's no dubbing.  It takes place in England.