Gary Cooper is "George Radcliffe" whose testimony at the Old Bailey sends a young, alcoholic "Donald Heath" (Ray McAnally) to jail for murder. Years later, his wife Deborah Kerr ("Martha") receives a letter in the post that was sent at the time, but delayed by a mail robbery, trying to blackmail her husband for the murder. Despite wanting to disbelieve this, she cannot quite dismiss the idea and the more uncertain she becomes, the more uncertain we become... There are some good supporting performances from Eric Portman, Hermione Gingold as "Lily" and Diane Cilento as "Mrs. Heath"; a well writt...