Once, after reading in a magazine that she was "the world's most mysterious woman," Agatha Christie complained to her agent: "What do they suggest I am? A Bank Robber or a Bank Robber's wife? I'm an ordinary successful hard-working author--like any other author." Her success was not exactly ordinary. She produced nearly 90 novels and collections of stories in a lifetime that spanned 85 years. One of her plays, The Mousetrap, opened in London in 1952 and is still running.
She refined and left a lasting imprint on the detective formula. An "Agatha Christie" became a shorthand description for an unadorned...