In wide release this Christmas will be the new film The Imitation Game (trailer), eagerly awaited by all serious fans of cryptography, World War II history-Bletchley Park division, spy stories, the invention of computers, and Benedict Cumberbatch. (My review of the movie.)Last week the author of the book on which the movie is based, Andrew Hodges, spoke here in Princeton. Hodges’s book—“one of the finest biographies of a scientific genius ever written,” said the Los Angeles Times reviewer—is Alan Turing: The Enigma: The Book That Inspired the Film “The Imitation Game” published in 1983 by Princeton University Press, which is congratulating itself heartily over its three-decades’-ago decision.

As you may recall, Alan Turing was the young British scientist (incorrect to label him a mathematical genius, because part of his brilliance was in blending fields—logic, engineering, biology, and mathematics) who led the successful efforts to break the Nazi naval codes in World War II. The machine created to do this was an early computer, and a paper Turing wrote in 1936 laid the foundation for the theory of computer science, by imagining a field that previously did not exist.

In Princeton in 1936-38, he worked on speech-scrambling technology. His interest in these diverse topics led him to an interest in ciphers and artificial intelligence, and these interests led not just to the Turing Test (“the imitation game”), but to Bletchley Park and the team of scientists there. Turing’s pivotal role in the Allied accomplishment, like most information about the unraveling of the Germans’ Enigma machine, was not revealed until the 1970s. Hodges said some of his theories about the connection between mathematics and biology were so advanced they are only now receiving attention in science.

Turing’s homosexuality caused few problems in the tolerant environment of King’s College, Oxford, but after the war, that changed. He held vast amounts of wartime secrets in his head, and it was a period of intense anti-Soviet paranoia. The authorities worried about his vulnerability. He died at age 42 of cyanide poisoning, and Hodges believes the coroner’s conclusion that his death was suicide, although the pressure that may have been brought to bear on him is unknown. He left just enough mystery about his death that his mother could console herself it was one of his science experiments gone wrong and conspiracy speculators could ever since consider it part of the enigma.