Watched The Fourth Man from The Agatha Christie Hour. About dual personalities. Set in a train carriage with flashbacks. Superb, subdued performances. The casting was great; despite limited action in scenes the performers' expressive eyes kept me riveted to the screen.

Here is proof that Alfred Hitchcock was greatly influenced not only by Sigmund Freud but also by Agatha Christie (who was influenced by Sigmund Freud as well).