For one thing, the audience knows for certain who is guilty from the first and so never questions whether or not the young man is guilty--we know him to be innocent. We also know that the father quickly fastens on the correct killer. The film then becomes both a race against time and a psychological battle between the father and the killer.
The film makes a strong contrast between the father and the killer, one that in any objective sense would seem to give the game to the killer. The father is a man whose life is in ruins, while the killer seems successful in every way. Stanford, the killer, is a successful industrialist who has risen through the force of his own personality and his willingness to do whatever he deems necessary to achieve his goals, clearly even to the point of murder. The one area of failure for Stanford is his marriage--he has married a woman socially superior to himself in order to achieve a higher place in Britain's stratified society, but he does not love her and is constantly irked by her pretensions and her condescension toward him. This personal failure is the one link he has with Graham. Stanford is always seeking to control every situation, and his wife is one thing he cannot control. The fact that he takes to Graham as he does reflects his need to control this situation as well. He knows who Graham is, and he kn