In 1981 in the Red Crow Indian Reservation, veteran Gisigu goes out on his boat to fish. When he comes back he starts cleaning the fish, but he’s shocked to see them move even though they’re missing their guts. Meanwhile Sheriff Traylor is called to check on his ex-wife’s dog.
He discovers the animal has been poisoned, so he shoots it to end its pain. Afterward Traylor visits his ex-wife Joss, who informs him their son Joseph has been arrested and they’ll only release him under his father’s supervision. Traylor gets in his car and gets a call from the station to inform him they’ve found a guy eating live chickens.
He also learns that his other son Lysol was arrested with Joseph, and that Gisigu called because he was scared of something. Traylor goes to see his father, who makes him look inside a box where all the supposedly dead fish are still moving. After deciding they should burn them, they go outside and notice the car trunk is moving too.
When they open it, the dead dog comes out and tries to attack, but Traylor quickly shoots it. Then they burn the fish and the dog together to stop them from coming back. In prison, Joseph and his half-brother Lysol hear their cellmate puking in the corner.
They think he’s just a drunkard, but suddenly the white man throws up lots of blood on the floor. At the reception, Traylor and Joss arrive to get the boys out, but when the officer says that Traylor gets arrested more often than a street worker, Joss says she’ll wait in the car. Then the officer explains Joseph was arrested because he climbed on top of a bridge and pooped on a passing vehicle.
The officer and Traylor go to the cell to release the boys and find the puking man unconscious on the floor. Suddenly he opens his now white eyes and attacks the officer, showing great strength as he easily overpowers the cop. Traylor rushes in to capture the man and Joseph punches him, only to get bitten.
Then the guy jumps back on the cop to bite him too, so the others rush to pull him back. The officer is furious and starts beating the man up with his baton until he’s unconscious again. Traylor has to drag the angry cop out of the cell, locking the door behind him.
Soon the creepy man wakes up and pounds on the door, so Traylor leaves with the boys. Later Joseph meets with his girlfriend Charlie, who is pregnant and considering termination. She hasn’t told her father about it yet because he doesn’t like her dating an Indigenous man.
The couple holds hands and decides to keep the baby. At the hospital, Joss is starting her nursing shift and notices they’re out of tetanus vaccines, which is a strange. A coworker explains today they’ve had an insane amount of patients with bites.
Suddenly Joss hears a noise and goes to the corridor to see people running away plus a patient attacking a doctor. In the evening Traylor goes to his friend Shooker’s house because his wife has been acting strange. Traylor rushes upstairs and is horrified to find the white woman eating her own baby.
As soon as she sees Traylor, she attacks him and manages to bite his arm. Every time he pushes her off she keeps coming back for more, but eventually Traylor manages to find an opening and runs out of the house. Soon the woman comes out as well and jumps on Shooker to immediately bite him too.
They roll on the ground until Traylor finally finds his shotgun and uses it to beat the woman to death. Afterward the men leave in the police car. Traylor calls the station and learns that his father has found some strange things, also Joss left a message saying “don’t get bit”.
When they arrive at the hospital, they find a dead man on top of the ambulance. He’s about to wake up, but Joss shows up and shoots him. Joseph is stuck inside the ambulance and there’s a patient behind him also attacking.
As Joseph gets bitten again, Traylor shoots the door open, allowing the boy to kick his attacker out. The woman tries attacking Traylor next, but at that moment Bumper arrives with a chainsaw and cuts her head open. Then the group meets with Gisigu at the bridge to burn the bodies while he explains that dead people are coming back to life.
Six months later, society has collapsed. It turns out all those attacks came from zombies, meaning the apocalypse happened. However Traylor and his people are doing fine regardless of the bites because Indigenous tribes are immune.
Now the Red Crow Reservation is a fortified compound. Moose and deer are clear to eat, but anything from the water is not. At the compound entrance, Lysol is taunting a soldier zombie that he’s hung with some chains.
He’s interrupted by the arrival of Joseph, who has brought three white survivors: Lilith, a man, and his young daughter. Lysol checks the girl and discovers the father had been hiding a bite, so he hits him with his weapon. After scolding Joseph for not checking properly, Lysol tells the man to kill his daughter or he'll do it.
Charlie comes to the man’s defense and wonders if Lysol would kill her baby if they’re born sick too. When Lysol says yes, Joseph punches him. An argument ensues until they’re interrupted by Traylor, who scolds them for fighting before announcing they must kill the girl.
This time Charlie does explain to the man that they have no choice, so he and Lilith are dragged inside. Bumper has a big axe but he feels bad about killing a kid. As the girl awakens as a zombie, Traylor grabs the axe and kills her.
Inside the compound, the father is told to burn the blanket with the girl’s blood. Joss interviews Lilith, who swears she hasn’t been bitten or eaten human flesh. However when she goes to the bathroom, she looks in the mirror to check on the bite she’s hiding.
Suddenly she hears a noise and when she checks on the stalls, she discovers the father self-deleted and now he's waking up as a zombie. Meanwhile Traylor and his team are discussing new ways of protecting the compound because every day the amount of zombies multiply. There already are guards on the walls that shoot them down and the body piles are growing faster than they can burn them.
At the bridge, Bumper is keeping up the blockade by using a harvester that shreds the zombies without wasting ammo. Living people are becoming a problem as well: because they hear the tribe is immune, they keep coming to the reservation asking for shelter and the numbers are getting hard to manage. The thing they’re needing the most at the moment is gas.
The meeting is interrupted when they’re informed of the zombie father in the bathroom. Traylor gets his machete out and brings the creature down. In the evening Charlie tells Joseph that Lysol has become more and more unstable since the apocalypse happened.
She also tells him how the other people in the compound treat her, explaining they think her baby will be a zombie because she’s white. Joseph comforts her and reminds her that his blood will make the baby immune. At the same time Traylor goes to see Joss because the zombie father hurt him and Joss takes care of the wound while they discuss their incoming grandchild.
It’s revealed that Traylor has dozens of scars he’s obtained by fighting zombies. Later Lysol complains about the amount of white people they’re allowing into the compound. He points out they’ll get tired of being “herded by Indians” and could turn against them any day now, not to mention just one liar could release the zombie plague in their home.
Traylor, Joseph, and Gisigu still think saving people is the right thing to do, but Joss agrees with Lysol. Tired of all the scolding, Lysol throws a party at his place that includes alcohol, Mary Jane, and happy powder brought by a dealer. He apologizes to Joseph for threatening the baby, but Jospeh thinks it’s the substances talking.
Lysol then shares a story about the day he used his mouth on a woman without knowing she was on her shark week. The naughty moment was interrupted when he got a call from his friends asking him to bail them out of jail, so Lysol rushed the station without hesitation. The police saw the blood on his mouth and assumed the worst, so they arrested him on the spot.
Then the dealer shares a little theory: he thinks the zombie plague wasn’t an act of god, it’s Earth getting back at humanity for how they've treated the planet. Moments later Joseph hears some screaming and goes to check on his brother, only to discover a zombified Lilith eating Lysol’s member. Meanwhile Gisigu, Traylor, Shooker, and Bumper are visiting an abandoned garage to look for gas.
Bumper ties a rope in front of the door and knocks it on before opening. When a zombie runs out, it trips on the rope and Traylor shoots it. Then he goes inside and finds bodies in every corner.
Suddenly a zombie falls in front of him and he quickly shoots it, only to realize it had already been dead. When he goes further inside, Traylor discovers his father has already killed all the zombies in the building. Back to Joseph, he’s trying to drag his brother to see Joss to take care of the wound, but Lysol keeps insisting that they need to raise the alarm.
He hugs Joseph as he apologizes, but it’s a trick to stab him because he blames him for bringing all those outsiders. Then Lysol and the dealer release Lilith on the compound so she can bite all the white people. A bleeding Joseph runs to the dorms and closes the door right before they hear chaos unfolding outside.
Joss tries to tell people to stay calm and reminds them that there’s an emergency exit, but a scared man runs through the front door anyway and immediately gets killed, his blood spilling under the door. Soon Traylor’s team returns to the compound and even through the closed doors they can tell it’s been overrun by zombies. They use the radio to call Joss, who explains she’s hiding in the basement with the survivors.
Shooker opens the main gate and Bumper plays some music in the car, causing the zombies to come out to check on the noise. As they climb on the car, Bumper begins driving so the zombies follow him away from the compound. Knowing there may be more, Traylor sends Shooker to get the truck while Gisigu kills a crawling zombie with his sword.
Then they enter the dorm building, where they kill more zombies at the door before going to the basement. They find Joss and Joseph pushing a door against a bunch of zombies, so Gisigu cuts their arms to allow Traylor to lock the door with his knife. They tell the survivors to run outside because the truck is waiting at the same time that Charlie starts feeling contractions.
At that moment the zombies manage to break the door open and Traylor has no choice but to open fire. The shots get the attention of other zombies in the compound, so Gisigu tells Shooker to drive away with the survivors. Two people fall off the truck in the process and get eaten by the zombies anyway.
Traylor drags Joss, Joseph, Gisigu, and Charlie to hide in the corridor to the emergency exit, but he can tell the door won’t hold for long and tells his family to leave without him. At the count of three Gisigu opens the door and Bumper appears in a car. Soon the zombies break down the other door and jump on Traylor to start feeding on him while Joss tries to hold his hand, but Gisigu forces her to let go.
The family leaves in the car while Traylor dies on the stairs. In the meantime Lysol, the dealer, and his fellow thugs have captured all the white survivors and a zombie. They force a woman to ask for help on the radio with a story about a massacre happening in church.
After Gisigu promises to help, Lysol hangs up and lets the zombie eat the woman. In the morning the dealer gets ready to burn down all the survivors, but his speech is interrupted when Gisigu cuts his head with a sword. Outside Joss tries to guide Charlie through her contraptions while Bumper guards them, but he suddenly gets a sword through his chest.
It’s Lysol, who drags Charlie out of the car before opening another vehicle’s trunk to release a zombie. Joss quickly opens fire, but she misses all her shots and runs out of bullets. The zombie jumps on Charlie and bites her neck before Joseph finally arrives to decapitate the creature.
Afterward Gisigu makes Joseph punish his brother with a dagger. Before getting stabbed, Lysol admits he let Lilith in on purpose and got the inspiration from Joseph’s relationship with Charlie. Then Gisigu shoots in the air to get the attention of the zombies, who run to feed on Lysol’s body while he’s still alive.
The family keeps moving on foot and reaches the shore, but sadly the only boat is on fire. Thankfully Shooker shows up on another boat, explaining he heard the shots. Joss, Charlie, and Joseph get ready to leave, but Gisigu refuses to leave his land again and chooses to stay.
After sharing an emotional goodbye with his grandson, Gisigu starts fighting the incoming zombies. He manages to kill a bunch of them, but the horde is big and eventually overpower him to eat him. During the boat ride Charlie gives birth to a healthy baby girl.
Joseph insists she should hold her, but Charlie only takes her for a second because she’s worried about her incoming transformation. After giving the baby to Joss, Charlie asks for mercy and Joseph has no choice but to shoot her. As the baby starts crying, Joseph has a breakdown.
