This atmospheric little chiller works because it doesn't answer questions. It lets the mysterious stay mysterious. It does this mostly through a fish out of water type plot where a bunch of journalists are investigating a small Polish village. English is not spoken, the inhabitants are not friendly and we the audience aren't blessed with subtitles so we are in the same boat as the characters. The journalists are there looking for a missing person.
What they find instead is inexplicable.
There's a fog like cloud that doesn't move. There is a statue of a demon within the cloud. When the inhabitants find out that they've visited "the shrine" they try to capture and kill them. The rest of the film is a very tense sequences of captures, deaths, and escapes.
This is a very good horror film that works hard to more than just violence. You find yourself thinking about it and the whys it never answers.