An interesting and sympathetic biography of Alan Turing. If I have a criticism it's that - as happens so often with science biographers - there's a temptation for the author to focus more on the results than the man. Leavitt's portrayal of Turing's personality makes for fascinating reading. His determination to slog through the ins and outs of the various maths is, while necessary, perhaps a bit unbalanced in places (and I like maths). Though I do make this complaint with a pinch of salt, as I must admit this book has one of the clearest explanations of the science behind Turing's universal machine that I've read... but the explanation just goes on and on, while I'm wanting to get back to the person behind it.