The film at the very outset projects a young woman named Charlotte "Charlie" Newton, living in Santa Rosa, California. The woman is frustrated because nothing seems to be happening in her life, but after a few days receives the news of his uncle, Charles Oakley's visit. Two men are shown while pretending to conduct a survey. Graham speaks to Charlie privately, identifying himself as Detective Jack Graham and informs her that her uncle happens to be one of two men suspected of being a serial killer known as the "Merry Widow Murderer". He is suspected with a modus operandi of seducing, murdering and robbing the wealthy widows. Though Charlie refuses to believe the entire story at first, but she also comes across and notice her uncle acting suspiciously on several occasions. In particular, during one family dinner conversation Uncle Charlie reveals his utter contempt for rich widows! In addition, the suspicions of young Charlie soon become apparent to Uncle Charlie and through confronting her once he admits that he is indeed the very person the police are after. At this moment the stern character of Charlie gets revealed. Though the Uncle begs her for help, she reluctantly agrees not to say anything, to avoid a scandal, as long as he leaves soon. This incident is followed by the news confirming the killing of the other suspect at the time of fleeing from the police, and is assumed guilty. Detective Graham leaves, and Uncle Charlie is relieved at first, until he remembers that his niece knows his secret. Soon, the young woman has a couple of potentially fatal accidents, falling down some steep stairs and being trapped in a locked garage with a car with a running engine. In ths last phase of the film, Uncle Charlie is found to announce that he is leaving by train for San Francisco. He forces his namesake to stay on board, trying to murder her by throwing her off. Instead, in the ensuing struggle, she pushed him away from her and he falls into the path of an oncoming train.
The film Shadow of a Doubt was aired on January 3, 1944 on the Lux Radio Theater of Cecil B. DeMille with its original leading actress and Wiliam Powell in the characterization of Joseph Cotten role. (We shall have to keep in mind that Patrick McGilligan said Hitchcock had originally wanted Powell to play Uncle Charlie, but MGM refused to lend the actor for the film.) Again later, in the year 1950, Shadow of a Doubt was featured as a radio play on Screen Directors Playhouse, that starred the legendary actor Cary Grant as "Uncle Charlie" and Betsy Drake as the younger, female "Charlie".