This is a study of a common recurring character type in British detective novels of the early twentieth century, by Agatha Christie, Dorothy Sayers, Ngaio Marsh, Margery Allingham, and Georgette Heyer. All of these novelists frequently feature women who distinguish themselves as heroines by acting like gentlemen. Few use the word explicitly, but all embody a remarkably consistent code of behavior and personality traits. Melissa Schaub discusses examples of the character type in a comprehensive range of novels by all five authors, and situates the Female Gentleman character type within both the emerging field of middlebrow studies and the history of nineteenth-century feminist literature, particularly the New Woman novels of the 1890s. Study of Female Gentleman novels ultimately leads to a new evaluation of the politics of classic detective fiction, and the place of the middlebrow novel in literary history and the history of feminism.