If you want a gentle introduction to the Cambridge Five spy scandal which effectively gutted the upper classes of Britain and savaged the faith of its ordinary citizens in the Establishment, consider The Real Spies Among Friends, a documentary of psychology as much as spycraft.
In this story, four alienated boys from what were technically the upper classes, although oftentimes they faced money troubles, who joined at Cambridge University through the magic of a rigid belief in Communism and eventually became the best spies the Soviet Union ever recruited.
They entirely compromised the British intelligence establishment, the nuclear program, and eventually, the CIA. The study of their personalities and the key events that sent this disaster stumbling on to its lugubrious conclusion (and the sad lonely deaths of the spies) drive this mellow but active film.
Tags: cambridge five, documentary, espionage, film
