I streamed the first season (six episodes) of Traitors (2019) on Netflix last night. The territory has been often and well mined - Britain right after World War II, struggling with Soviet infestation of secret services in London, American sense of entitlement to the point of bullying the Brits, and the shift from the conservative Torys to the leftist Labor Party in power. Probably the best of these shows was Michael Kitchen's long running (2002-2015) Foyle's War. Traitors is the best I've seen of a new kind of rendition of this story, probably truer to actual history, with far more violence and deaths at hand, in expected and unexpected places.
Emma Appleton does a great job as Feef Symonds, "A British civil servant [who] agrees to spy on her own government for the Americans in the aftermath of WWII". She's in bed and in love with an American officer (married) and recruited by his boss, ruthless spy-master Rowe, who couldn't be better played by Michael Stuhlbarg (Boardwalk Empire). Actually, he's not quite yet a spy-master. His goal is to create from the wartime American OSS the CIA, with eyes and ears everywhere in the world, to report on and deal with the burgeoning Soviet menace, which he sees as the main threat to democracy with the Nazis now vanquished.
He's not wrong. In both real history and Traitors, Soviet sympathizers and out-right spies already abound in British government - e.g., Kim Darby - and don't hesitate to mete out death to not just enemies but inconveniences. Rowe is pretty much the same, and this tension between two cunning and brutal adversaries, with Britain and thus Feef in the middle, is the platform, ambience, and essence of Traitors.
The narrative is animated by current events, ranging from Truman dropping the A-bomb, to the British midwifing the state of Israel, and they're all shown with the familiar British bristling to American arrogance, which often comes from the mouth of Rowe. The dialogue is sharp and funny when it needs to be. Even the secondary characters are memorable (especially good work by Keeley Hawes), and when you catch your breath after the last episode you'll be glad if not happy you saw this.