This New York Times–bestselling biography of Alan Turing, written by Andrew Hodges, captures both the inner and outer drama of Turing’s life. It tells how Turing’s revolutionary idea of a universal machine laid the foundation for the modern computer and how he brought the idea to practical realization in 1945 with his electronic design. The book also tells how this work was directly related to Turing’s leading role in breaking the German Enigma ciphers during World War II, a scientific triumph that was critical to Allied victory in the Atlantic.