I think everyone has heard of the unfortunate real-life events of the Donner Party and how some of them resorted to cannibalism in order to survive being trapped in the mountains, in winter, while trying to get to California. This movie deals with a group of them, a dozen or so, who are part of the original 82 settlers (only half of them made it to California).
Crispin Glover is Foster, who is the ultimate bad guy of the bunch, justifying everything he does. In fact, he's the one who kills the others who become lunch. It isn't like someone died and they decided to eat him....it's a very premeditated act. This actually surprised me, since I assumed they just ate the people who died of exposure. Eddy is the "hero", though he ends up eating people meat when he's starving. Not a lot is shown, it's all just implied. DONNER PARTY is a grim character study of a group of desperate people and one of the better movies on the subject.