In "Sister", we find 12-year-old Simon living a desperate life with his sister Louise in cheap public housing in an industrial town near (but literally below) a ski resort inhabited by the ultra wealthy. Louise works sporadically cleaning ski chateaus, while Simon seems to be the main breadwinner through his dubious job of swiping ski equipment and selling it as a one-man black market.
This sad story is presented in an atmospheric, minimalist way, making full use of the picturesque setting, yet managing to make the grandeur of the mountains and the luxury of the ski resort mostly just serve to make the viewer aware of the sadness of the two main characters.
The movie is definitely sociological in nature, making the viewer wish some outside party would intervene and help with this horrible situation. No particular moral or message is presented, I'm not sure one is implied even subtly, except that the world can be a very sad place for people at the bottom, even in a place like Switzerland that is often portrayed as an ideal society (it certainly isn't in this movie).
The only fault I could really find was that the movie dwells for so long on Simon's thefts in the first half of the movie, which are not all that entertaining, and beyond establishing that his life is like that, I'm not sure that we really needed the full 45 minutes of him being a ski resort kleptomaniac. Nothing else in the movie felt unnecessary, or even worthy of criticism... for what it is trying to be, this movie is quite good, especially in the second half.
My only advice is to not expect anything upbeat. I found this movie rather depressing. That hardly means it's not a good movie, of course. Just brace yourself for one sad slice of life.
