This movie possesses a striking harshness—not due to excessive violence or gore, but stemming from the way it portrays both admirable and deplorable qualities in people (like strength, resolve, disloyalty, abandonment, desire, etc.), all set against an impressively realized depiction of a brutal Missouri winter. Leonardo DiCaprio plays "Glass," who suffers a vicious bear attack while hunting with his group. Afterward, he's left for dead by his companions. His survival depends on employing his natural abilities to navigate the wilderness and confront hostile Native Americans in order to reach safety—all driven by an intense need to get even with those who left him behind. Iñárritu guides this story with a good deal of expertise; you become completely absorbed in "Glass’s" fight for existence, and then in his quest for vengeance against Tom Hardy's character, "Fitzgerald," whom he holds responsible for what happened. Perhaps the director intends to suggest similarities between how people treat one another and how they treat the natural world—and that there isn't much distinction in the regard shown to either; however, I don’t think that’s really central to the experience. It's a tremendously entertaining, story-focused, realistic film that develops deliberately and steadily toward a satisfying conclusion, leaving me feeling chilled.

Source on TMDB