Just rented it and had to watch it three times. An amazing film! Where's the DVD version! This simple grim tale a man wrongly imprisoned for robbery and the heart-breaking subsequent mental breakdown of his wife will haunt you. I would argue that this film demonstrates Hitchcock's films in its purest form. No bird attacks or shriveled corpses here but then some of us who love Hitchcock's works believe they are really in the end about people and how they survive, or come to be trapped by, dire circumstances. Watch this movie along with "Vertigo," "Psycho," "The Birds," and "Marnie." Like "Psycho" and "The Birds," we see both physical and psychological imprisonment of the characters (or being caught in a kind of trap might be the relevant metaphor here) and like "Vertigo" and "Marnie," we see the overwhelming power of mental disturbance have on one's ability to control one's own life. I have found that it always helps to compare Hitchcock's films with each other as certain themes seem to occur over and over again, almost as if Hitchcock had some compusive fixation on it.
I would consider this film a great tragedy.