Hitchcock brilliantly transformed this from a theatrical experience to a cinematic experience that is still quite staged in its flow and overall setting, but it works so well that it’s really hard to criticize, as he constantly finds new angles from which to shoot the small apartment to keep the visual element of the work fresh and interesting. 

The performers all provide career-best efforts, particularly Ray Milland, whose cool, relatively calm demeanor throughout the story, specifically in the closing scene, is a highlight.

The scenario is completely elaborated in the opening scenes, yet the suspense is never removed from the piece until the conclusion.

Not as good overall as Hitchcock’s other effort of 1954, Rear Window, but this is still a very good film and ranks highly for me in his filmography.