The Man With The Twisted Lip by Arthur Conan Doyle

A woman’s husband vanishes after entering an opium den, and all clues point to a disfigured beggar seen at the scene. Holmes investigates and uncovers that the beggar is actually the missing man—living a secret double life to escape the pressures of his respectable existence. The plot builds on disguise and deception, with a surprising yet plausible twist. Doyle explores themes of identity, respectability, and choice. It’s one of the more unusual and socially reflective Holmes stories.