A widow (Michele Morgan) in a small town begins to realize that her late husband was hated by nearly everybody. She begins to receive blackmail letters that threaten to further humiliate her if she does not pay up. She enlists the help of Franz (Robert Hossein), a man who was once fired by her late husband, to track down the source of the letters. She becomes unhinged and eventually tries to kill the man who is helping her in this early example of a Giallo.