Cause For Alarm | 1951
An ailing man becomes obsessed by the paranoid notion that his wife and doctor are having an affair. He then writes a letter to the D.A. accusing them of plotting to kill him. After his wife mails the letter for him, he begins telling her what it said, and in the process gets himself so worked up that he has another heart attack and dies. Although she is innocent, she must nevertheless find a way to get the letter back.