The Spy Who Came in From the Cold
Having just come back from Berlin last week, this movie has a special meaning for me. John le Carre's famous 1963 novel was made into a film starring Richard Burton. Highly acclaimed, the film won four BAFTA awards including Best Film.
The film depicts a British agent (Richard Burton) being sent to East Germany as a defector to sow disinformation about a powerful East German intelligence officer. Helped by his unwitting English girlfriend, an idealistic communist, he is recruited by the East Germans. His charade unravels and he admits to being a British agent.
The film is set in London and East Berlin. The whole film can be found on youtube. It's a British film and the actors speak very clearly (Richard Burton is one of Britain's most famous film stars but was also very well known as a Shakespearean actor).
The novel became famous for how it portrayed espionage methods as morally inconsistent with Western democracy and values. It became an international best-seller and was chosen as one of the All-Time 100 Novels by Time magazine. https://en.wikipedia.org/wiki/The_Spy_Who_Came_in_from_the_Cold