If you put a few people in a hole in which they can't escape, and provide only water for a month, what would they do? The movie covers the concept and quite effectively at that, with the ending, the sort I normally don't like in horror movie, quite satisfying. Oh, they do end up eating each other. I kept thinking I'd rather die, but maybe that's because I don't know the pain of hunger. But screws that, I'd commit suicide first. That seems an easier solution.
The movie is very low-budget and feels like its made by students, but the acting is quite good. It would have benefited from decent cinematography.