A concise, accessible account of a pioneering mathematician and logician that follows his intellectual development from Cambridge to his 1936 formulation of the abstract ‘Turing machine’ and its decisive role in defining computability, describes his wartime work at Bletchley Park breaking German ciphers, and surveys his postwar efforts to build electronic computers and to explore machine intelligence (including the Imitation Game), while also examining the social, legal, and personal forces that curtailed his career and shaped his legacy.