The Upturned Glass (1947)

James Mason is both measured and potent in this crime story of a brain surgeon "Michael Joyce" who performs a life-saving operation on a young girl. He falls in love with the girl's (married) mother "Emma" (Rosamund John) and when she is found dead at the foot of her bedroom window one day, he begins to question the verdict of suicide and determines to get to the bottom of what really happened. It's told by way of a retrospective - he is lecturing his students about a "fictional" case of murder where the killer is sane and calculating - and that gives the story quite a bit of pace and menace. The plot isn't complex and the audience is left in little doubt about what happened/is going to happen - but Mason along with Pamela Mason as "Kate" - the rather odious sister-in-law, manage to create quite a cumulative effect as the story develops that left me in no doubt that right was done!