The recent film The Imitation Game stars Benedict Cumberbatch as Alan Turing, a British mathematical genius who helped the Allies win World War II by working to break the German Enigma code. After the war Turing was persecuted for his homosexuality, and subjected to cruel and degrading treatment that led him to take his own life. Last year Turing received a posthumous pardon from the Queen, and his legacy endures in such areas as mathematics, computer science, and artificial intelligence. One of his admirers is Walter Isaacson, whose new book The Innovators profiles Turing and other digital pioneers.