In the story, a young man named James McCarthy is arrested for the murder of his father. Alice Turner, James McCarthy's friend, believes that he is innocent. She asks Inspector Lestrade of Scotland Yard to investigate the murder, hoping that he can prove James McCarthy's innocence. Inspector Lestrade asks the brilliant consulting detective Sherlock Holmes to help with the investigation. Lestrade becomes convinced of James McCarthy's guilt. Holmes, however, believes it is possible that the murder was committed by someone else. Through consideration of the evidence and examination of the crime scene, Holmes discovers the murderer's true identity.