The Passenger (Pasazerka)
The director died during filming, the incomplete film is "finished" with photos and narration in what could best be described as a rough cut, there are no English subtitles, and it's hard to find. (I bought my copy from an ebay seller in Poland.)
But, if you can find it, the film is definitely worth watching.
Unlike Hollywood movies, this Polish movie really shows just how perverse and evil the German Socialists were. As for the film, while action is happening in the foreground, the camera shows in the background the day-to-day torture and tormenting of the prisoners. (The photo is of the DVD copy I purchased.)
And if you can't find The Passenger, I urge you to watch the movie I previously posted the link for: The Katyn Massacre, another Polish movie that illustrates how the German Socialists methodically and brutally exterminated the ethnic Polish elite (mostly Catholics) and targeted their families. I highly recommend this movie. The Polish really understand what happened, and this film has a real verisimilitude to it and not some Hollywood hokum.