Well, nice people don't go murdering other nice people.

The Paradine Case (1947)

Chosen by Emma Jones who had this to say: 'I have always been an avid Hitchcock fan and whilst some of his films I've watched once or twice and appreciated the craft and skill of his work (Birds, Psycho, Marnie) others I watch on an alarmingly regular basis (Notorious, Spellbound, Rear Window, Vertigo, Rebecca). The Paradine Case falls into the regularly watched category!

One reason i love this film is that I cannot resist a Gregory Peck film. There is something comforting about him, and you know that you are in safe hands. Ann Todd is also excellent as his humiliated but understanding wife.The Paradine Case is a well-crafted courtroom drama but it also has depth and a very dark core. Some of the darkness comes from an extremely sinister performance from Charles Laughton as a sleazy, cruel and nasty judge. I have often thought that this performance was close to his own personality (sorry Charles if you were a thoroughly nice chap).'

Like a proto-erotic thriller. This like Emma's last recomendation Intermezzo is both coy about it's central stories infidelity and surprisingly blunt (I think we expect everything that's 'old' to be really twee about sex).
That said beyond some good performances (Peck is good, Laughton is terrific) Hitchcock's heart didn't seem in this one. It's rather perfunctionary and may have aged badly due to all the hokey cliches that have become commonplace since.