London, 1960s: when British civil servant Samuel Fennan is denounced in an anonymous letter as a former Communist, MI5 sends Charles Dobbs to discuss it with him. After a genial meeting, Fennan apparently kills himself, and Dobbs sees contradictions. He begins to investigate: was Fennan a spy after all? Was he murdered?
Sydney Lumet directs a glittering 1960s megacast - James Mason, Maximillian Schell and Simone Signoret - in a brooding espionage mystery. Vintage stuff.