They played a vital role during the war, helping to crack the military secrets of the Nazis. But what happened to the codebreakers of Bletchley Park in Buckinghamshire, in the years that followed?
Well, that's the theme of a new murder mystery drama starting at 9pm tonight on ITV1. Malcolm Shaw was given special access behind the scenes, during the making of the programme.
VIDEO: The women who helped to end the Second World War.