One of my favorite locked room murders, because I am such a Martin Beck fan, is THE LOCKED ROOM. by Maj Sjöwall, Per Wahlöö,
In one part of town, a woman robs a bank. In another, a corpse is found shot through the heart in a room locked from within, with no firearm in sight. Although the two incidents appear unrelated, Detective Inspector Martin Beck believes otherwise, and solving the mystery acquires the utmost importance. I am not sure this one would rank with the greats but setting and character rate high with me.
What are some other great ones?
Forgot to post my movie review of THE BLUE ROOM.