I really enjoyed the movie The Lives of Others (2006). It is about a German Stasi agent before the Berlin Wall fell. He sets up a surveillance to get some dirt on a playwright and his girlfriend. It gives a glimpse of how bad thing can really be in a police state. The story has some interesting twists. I really enjoyed the story, but you have to read the 2h 15m movie because the dialog is in German with English subtitles.