Geniuses At War by David A. Price
I am currently in the middle of reading this book and I have to say, it is one of the most interesting and educational books I have read this year. It is about the GC & CS during and leading up to WW2 at Bletchley Park. It goes through the code breaking of the enigma machine, a little background of Alan Turing along with others, and the overall breakthroughs in technology due to the need to decipher the Axis power encoded messages.