Book excerpt: Alan Turing is a patron saint of Manchester, remembered as the Mancunian who won the war, invented the computer, and was all but put to death for being gay. Each myth is related to a historical story. This is not a book about the first of those stories, of Turing at Bletchley Park. But it is about the second two, which each unfolded here in Manchester, of Turing's involvement in the world's first computer and of his refusal to be cowed about his sexuality. Manchester can be proud of Turing, but can we be proud of the city he encountered?