Richard Bilton speaks to leading figures from the shadowy world of secret intelligence to find out about modern surveillance and to see just how effective it is in tackling serious crime and terrorism.Intelligence insiders reveal the difficult task they face with an ever-evolving threat and a constant arms race between the state and criminals over surveillance technology.The programme explores how, increasingly, modern surveillance relies on computer databases watching and recording everyone, not just the criminals and terrorists. Richard Bilton talks to former insiders who question the government's argument that if you have nothing to hide you have nothing to fear, and who say it is an argument for total surveillance and a total security state.