The team of trappers Glass is with in the North American wilderness is attacked by a posse of American Indians, and the Europeans return to their boats, abandoning many of the pelts they have made. On the advice of Glass, the survivors leave the boat they are in and set off across-country but Glass is badly mauled by a bear - these scenes are terrible, and are not for the squeamish, and set the tone for violence for the rest of the film - and his mates eventually leave him in the care of two of their number, namely John Fitzgerald (Tom Hardy) and a youth named Bridger (Will Poulter) on the promise of a reward of $100 from the Hudson Bay Company, who the captain (Domhnall Gleeson) works for. This is fine but Fitzgerald is greedy and convinces Bridger to abscond, leaving Glass for dead. Fitzgerald also kills Glass' mixed-race son, Hawk (Forrest Goodluck).
At the same time as Glass is trying to return to the European town a group of American Indians led by Elk Dog (Duane Howard) has been searching for Elk Dog's daughter Powaqa (Melaw Nakehk'o). Although they have a different goal from Glass his route crosses theirs at multiple points, notably at the end of the movie where the connection finally adds a deep note of irony to the tale. No story about North America in the 19th century can ignore the plight of the American Indians, of course, but this movie is exceptional in its attempt to imbue its representatives with humanity and humour.
This thread in the tale is examplified especially well by the character named Hikuc (Arthur Redcloud). Having escaped from Elk Dog's group in one episode by fleeing in the current of a large and fast-flowing river, Glass gets back to the bank only to come across a stampede of buffalo. He sees a beast being brought down by wolves but then goes to sleep, exhausted. He is woken later by strange sounds and walks to the top of the bank he has been sleeping on to find a man has chased away the wolves and is feeding on the carcass of the dead beast. Glass approaches despite the man's threatening gestures, begging for food. The man throws him a hunk of raw meat and he eats it. In the morning Hikuc tells Glass they will from thenceforward travel together.
Hikuc is a skilled survivor who understands the land he lives on, and is able at one point, during a blizzard, to help cure Glass' wounds by applying some grasses to them. Hikuc ensconces Glass is an enclosure made from branches and sticks and builds a fire to heat rocks, creating a steam bath that Glass sleeps within. He wakes refreshed in the morning but what happens to Hikuc is less uplifting.
It is in the short episodes of the movie like this one that its true art lies. The movie has a disjointed rhythm like a set of disconnected narratives. Often the only thing joining them together are the stunning vistas of nature the filmmakers create with their cameras, balancing them on the themes of a wonderful soundtrack that owes much to Modernist 12-tone music.
While Glass eventually returns to meet again with Fitzgerald - the man he has ostensibly been chasing the whole time - the set-piece action sequences that conspire to create this particular narrative arc are less important than other elements of the movie, notably its earlier vignettes about life among a foreign people in a foreign country.