NOTE: This spoiler was submitted by Jeremy
The film starts with Hugh Glass (Leonardo DiCaprio) speaking to his son Hawk (Forrest Goodluck) in an Indian language, telling him that even though he is scared and wants his trouble to be over, he must fight as long as he can grab a breath. As we hear Glass' voice, we see images of Glass with his wife and son, his home being set on fire, and him holding his wife in his arms.
Glass and Hawk are walking through a river with other men from their hunting party as they stalk wildlife. They live on a settlement with other fur-trappers. They are led by their captain, Andrew Henry (Domhnall Gleeson). A man from their party walks into the settlement and collapses forward with an arrow in his back. Another man is shot in the neck with an arrow and falls into the campfire. The hunting party is attacked by a tribe of Arikara Indians. The men fire back with their rifles. Glass is attacked and nearly choked to death, but one of his men rescues him. The surviving men gather their furs and materials toward a boat to make their escape.
It is learned that the Indians are looking for the chief's daughter, Powaqa, thinking that one of the men from the hunting party may have taken her.
The men seek out a new settlement. Hawk is antagonized by John Fitzgerald (Tom Hardy) for his race (Hawk is half-Indian on his mother's side), but Glass quickly defends his son and tells him not to retaliate against Fitzgerald.
Glass is later separated from the party in the woods. He comes across a grizzly bear and her cub, and he is quickly attacked by the larger bear. The bear claws and bites into Glass, throwing him around as Glass tries to defend himself. He manages to shoot at the bear, but it doesn't kill her. She attacks again, and Glass gets his knife, stabbing it to death as they both tumble down a hill. The men later find Glass and try to tend to his deep wounds.
The Indians continue their search for Powaqa. They come across French fur traders and try to trade for their horses, but the men in that party refuse to give up their horses.
The men in the hunting party carry Glass on a makeshift stretcher, but he only slows them down. They attempt to carry him up a hill, only for him to slide and bring the other men down. Fitzgerald suggests they need to just kill Glass and put him out of his misery. Henry covers Glass' eyes and almost shoots him in the head, but he cannot bring himself to do it. Henry offers payment to anyone who can stay behind with Glass. Hawk and Jim Bridger (Will Poulter) volunteer, though Fitzgerald points out that they and Glass will be likely to die. Henry raises the payment offer so that even Fitzgerald decides to stay with them until Glass expires.
Glass is still in great pain and continues to have visions of his wife and the day his home was burnt down.
Fitzgerald gets a moment alone with Glass and convinces him to let him put him out of his misery so that no one else is slowed down or left waiting to die, including Hawk. Glass blinks in agreement, and Fitzgerald starts to smother him. Hawk shows up and thinks Fitzgerald is deliberately murdering his father. Hawk starts to call Bridger for help, leading to a struggle with Fitzgerald in which the man stabs Hawk in the abdomen, then letting him bleed out to die as Glass watches helplessly. Fitzgerald gets rid of Hawk's body and tells Bridger he doesn't know where he went.
Later that night, Fitzgerald urges Bridger to move on with him as he claims to have seen Ree Indians by the creek. Already having dug up a grave for Glass, Fitzgerald forcefully drags him into the hole and buries him under a pile of dirt as Bridger reluctantly lets him do so.
We see Henry and the hunting party have arrived at their outpost. As Fitzgerald and Bridger head to meet them, Bridger realizes Fitzgerald was lying about having seen the Ree by the creek. He turns his rifle on Fitzgerald, but he takes it from Bridger and turns it on him. He pulls the trigger, only to see that the rifle was unloaded. They continue to move.
Glass awakens and weakly struggles to rise from out of the dirt. He starts crawling his way through the woods to find food and warmth. He finds Hawk's body freezing up from the cold. Glass vows to stay by his son's side. He finds a thick fur pelt to take with him to keep warm. As he continues to move, he feeds off of roots. He attempts to build a fire for added warmth. Nearby, the Indians are getting closer, so Glass rides down the rapids to escape them.
Fitzgerald and Bridger are still walking. They come across a burnt-down settlement with bodies sprawled across the ground. One woman emerges from her burnt hut and sees the men.
Glass is getting colder and hungrier. He walks into the river and eats a live fish. He walks up a hill and sees a Pawnee Indian feeding off the carcass of a bison. Glass approaches him cautiously and gestures for food. The Indian throws him an organ, which Glass eats despite feeling disgusted. In the morning, the Indian observes the bear wounds on Glass' body, which are starting to rot. Glass says his men left him for dead and killed his son. The Indian states that his own family were killed by Sioux. He is seeking out more Pawnee.
Fitzgerald and Bridger reach the outpost and rejoin their party. Fitzgerald tells Henry that they couldn't save Glass or Hawk, and he collects his payment. Bridger, however, remains utterly remorseful.
Glass and the Indian move forward. They spend the evening sitting and catching rain in their mouths. This is the first time Glass has looked peaceful in a while. The Indian gathers materials for warmth, and as he tends to Glass, Glass starts hearing his wife's voice, and then sees himself walking toward Hawk before they embrace.
When Glass wakes up, he sees that the Indian has been hanged by the French fur trappers. He infiltrates their camp and witnesses one of the men raping a woman. It is Powaqa (Melaw Nakehk'o). Glass holds the rapist at gunpoint and lets Powaqa go. Glass then takes a horse, letting the other horses loose. He rides it to a spot in the woods where he builds himself a fire.
In the morning, the tribe searching for Powaqa starts to attack. Glass holds them off with his rifle before he mounts his horse and rides away. The tribe follows him on their horses up to a cliff where Glass and his horse fall over the edge. The horse dies, and Glass is more injured. As the night falls and the cold intensifies, he cuts the horse open, removes its organs, and stays inside its carcass for warmth. When he wakes up, he gets out of the carcass and moves to a cave. In there, he carves "Fitzgerald killed my son."
Some time later at the outpost, one of the French hunters arrives with Glass' canteen, which Bridger left on the dirt pile after Fitzgerald buried him. Thinking he took it from Hawk, Henry leads a search party through the woods. There, they find Glass, crawling on the ground weakly. They bring him back to the outpost. Henry finds that Fitzgerald is gone. The French hunter tells him that he heard Fitzgerald was headed to Texas. What's more is that Fitzgerald cleaned out the party's payroll safe. Henry then confronts Bridger with his rifle and beats the boy to the ground as he tells him that Fitzgerald lied to him.
Glass vouches for Bridger's innocence to Henry, stating that he was only following orders. He also tells Henry how he saw Fitzgerald kill his son. Hearing that Fitzgerald is heading for Texas, Glass requests that he seek the man out himself. Henry reluctantly agrees, but then decides to join Glass in the hunt.
The two encounter Fitzgerald and split up to get him from opposite sides. Henry finds Fitzgerald first and plans to bring him back to be tried for murder. The two men draw their guns on each other, with Fitzgerald killing Henry. Glass finds Henry's body and puts him back on top of his horse. They ride on in view of Fitzgerald, who fires his rifle at them. He thinks he's killed Glass, but he just shot Henry's body. Fitzgerald retreats, and Glass pursues. They corner each other in the woods, and Fitzgerald shoots at Glass. Fitzgerald runs down by the creek where Glass gets him and they begin to fight. Fitzgerald nearly stabs Glass, but Glass turns the knife on him. Fitzgerald impales Glass' hand, but Glass overpowers him and nearly finishes him off until Fitzgerald states that killing him won't bring his boy back. On the other side of the creek, Glass sees the Indians that have been pursuing him the whole time, now with Powaqa. He decides that revenge is in God's hands, so he pushes Fitzgerald into the water and lets him float over to the Indians. The chief grabs Fitzgerald and kills him with his knife. They spare Glass.
Although he has gotten his revenge, Glass is alone once again, wandering through the cold land. He falls on his knees and sees a vision of his wife once again. The final shot is of Glass' eyes filling up with tears as he breathes heavily and looks toward the audience.