Rent The Spying Game: MI5 (2005)

MI5's counter-intelligence war was launched nearly a hundred years ago in an era when the messages sent by enemy spies were written in secret ink. Forty years later, MI5 achieved one of the great intelligence successes of World War II when its Double Cross system comprehensively bamboozled Nazi Germany. Over 50 years were to pass before MI5 officially admitted its own existence as the UK's primary agency against threats to national security. In the post-Cold War era, it has had to adapt and constantly modernise itself in its fight against terrorism and international crime. But one thing is for sure - the MI5 will remain in the front line against enemies which threaten the defence of Britain.