Just when you think you've seen all the great noirs: Witness to Murder (1954).
The setup comes right out of Rear Window, released at the same time. Barbara Stanwyck wakes up in the middle of the night, and sees, in the window across the way, a man strangle a woman to death. She runs to call the police, but by the time they arrive, there is no body. The killer, George Saunders, knows that he was observed, and has taken steps. He is a debonair and charming author, and the police reluctantly agree that Stanwyck was probably just dreaming.
By the way, the police are Gary Merrill as the clever detective, with the dumber partner played by the Maytag Repairman himself, Jesse White. Merrill has a great face for a detective, very "just the facts, Ma'am," very Joe Friday. In fact, Jesse White goes out the door muttering, "Dum da-dum-dum, 8:05, left office looking for trouble. 8:06, we find it!"
So Stanwyck knows she's seen a murder, but can't prove it. Saunders knows she's seen him, but he's a Nietzschean ubermensch and sets up a Gaslight campaign to destroy her. This lands her in the looney bin for "observation", where she is cooped up with a bitter nympho, a vacant old lady and Juanita Moore, singing a sweet sultry blues number. This snake-pit scene is the most noir in the movie, but the whole thing is drenched in shadows of venetian blinds and similar conventions.
Stanwyck is too old to be an ingenue here, she is a mature single career woman, which nobody makes anything of, but doesn't that indicate "repressed, hysterical spinster" to you? She plays it right down the middle - not a scared little girl, not a hysterical old maid, just an ordinary, intelligent woman with the deck stacked against her.
But Stanwyck and Saunders don't stop this from being a B-movie - just the kind of B-movie I love.