The Lives of Others is such a film.
Written and directed by Floran Henckel von Donnersmarck this film is a must for anybody with the remotest interest in European history and politics, especially the history of the Cold War era. It is set in the 1980s, just before Gorbachev came to power and started the process that would lead to the liberation of Eastern Europe.
If you are planning to visit Berlin I would urge you to visit the Stasi Museum. That museum and this film, chillingly illustrate the terrifying consequnces for the populace when the state takes control of every aspect of peoples' lives. Both should be compulsory for anybody who takes personal freedom for granted.
The Lives of Others tells the story of Stasi officer Wiesel who is tasked with eavesdropping on the daily life of writer Dreyman, thought by the authorities to be loyal to the DDR. Wiesler's experience mirrors the dawning realisation of millions of people behind the Iron Curtain in the 1980s, that maybe something is lacking in their Workers Utopia.
The film is chilling in the extreme and the last line, uttered by Wiesler, has to be one of the simplest but most pignant last lines in any film I've ever seen. You will be heartened, appalled and sickened at various times during it, but you really must see this film.