This story, considered by Arthur Conan Doyle to be his best Sherlock Holmes mystery, features one of his most creative (and unlikeliest) murder plots. Thirty-year-old Helen, Holmes’s client, is a victim of Victorian attitudes towards women. Fearing for their future, her dead mother had decided that she and twin sister Julia would not receive their inheritances until they married. Their violent stepfather, who manages the money, will become destitute should either of them wed. After announcing her engagement, Julia dies under mysterious circumstances. Helen fears that she will be next. Themes: decay, isolation, fear, murder, class, greed, hasty judgement, justice.

In this mystery by Arthur Conan Doyle, an English squire from a highly respected family asks Sherlock Holmes for help. His new bride has been receiving messages written in a strange code that appear to terrify her. The woman, an American, refuses to discuss her past, and a condition of her marrying him was that he must promise never to ask about it. Holmes takes on the case and easily cracks the code, but doesn’t move quickly enough to prevent a murder. Themes include honor, shame, secretiveness, fear, unrequited love, obsession, crime and justice.

A common theme in most detective stories is superior observation skills and deductive reasoning. A defining feature of Arthur Conan Doyle’s Red-Headed League is the way the facts presented by the gullible Wilson appear so bizarre to Watson as to defy interpretation. This prompts Holmes’s to quip: Omne ignotum pro magnifico [we exaggerate the importance of the unknown]. Once he dismisses the Red-Headed League as a distraction, identifying the crime in progress becomes a straightforward matter for the great detective. Other themes include deception (appearance vs. reality), gullibility, greed (of both the criminals and Wilson), crime and justice.