Don Castle is sharing a cheap room with his ex-lieutenant from the army, Wally Cassell. Castle is studying on the G. I. Bill. Cassell drinks a lot. Each is dating Bonita Granville, but it's all right, since she's twins in this movie. One is nice, the other is nasty. Then the nice one gets murdered, and detective Regis Toomey is on the case.
This being derived from a Cornell Woolrich story, it's surprising the guys aren't twins also; it would have saved on actors' salaries, although the process shots might have eaten up the difference. Miss Granville -- soon to become the wife of Jack Wrather, the producer of this movie -- is doubled by showing the back of another actress, or having her voice come from offscreen.
Of course, many odd possibilities arose in my mind. Did one sister kill the other, and then masquerade as the victim? What is John Litel doing in the cast? I started out confused, and even after the ending, I was still confused, because this was directed by John Reinhardt, who liked to throw in every film noir trope whether it should be there or not. Always watchable for the sake of Woolrich's sick symbolism, it's not one of the best noirs I've seen.