In the near future, a viral outbreak brings the zombie apocalypse to the world. All over the land,
people are trying to reach the quarantined zones, usually in buses guarded by the military. Friends
Jack, Patrick, and Emma with her baby are on one of these buses trying to reach a quarantined town
called Harmony, but the bus stops when they reach the gate for some reason. When the first soldier
goes out to investigate, he takes too long to come back, so the second soldier goes out to check and
ends up being attacked by the first soldier, who has become a zombie. This soldier tries to get
into the bus as well, but Jack and Patrick quickly push it out. Once the zombie is gone, Jack goes
out to get the firearms from the soldier, but the guy suddenly comes back to life as a zombie and
attacks him. After shooting it, Jack notices more zombies coming, so he hides under the bus while
Patrick closes the door and everyone inside the bus panics. Unfortunately, closing the door isn't
enough because the zombies just break the windows and bite everyone they can reach. While Jack and
Patrick fight off the zombies to the best of their abilities, Emma runs away and hides inside an
abandoned jeep with the baby. She thinks she's safe there but this safety doesn't last long:
the zombies reach through the windows and grab her too. By the time Jack arrives and kills them,
it's too late: Emma has been bitten. Nine years later, all the zombies have died from the cold.
Patrick lives in a house in the freezing town of Harmony with a dog, hunting whatever he can put
his hands on, even horses. He also has a radio that he tries to use to find other survivors,
but so far it's been pointless, and Patrick often ends up talking to himself. In the house
next door, Jack lives with Lu, Emma's baby who is now a young child and calls Jack "dad". They have
quite an amount of provisions, although some of them are starting to go bad, and Lu wishes
she could have more toys and other kids to play with. Jack makes sure to keep up Lu's education,
teaching her everything from Math to Geography. Patrick likes to spy on them with his binoculars,
wishing he could be with them instead of alone and grumpy. Lu has a secret of her own too: she
has befriended Patrick's dog, and sometimes she brings him cookies and other food through a hole
in the fence only she knows about. One morning, Lu discovers the dog has dug deep enough under
the hole for him to be able to go through it if he wanted to. Besides teaching Lu, playing with her,
and telling her stories of the old world, Jack also keeps himself busy by practicing his shooting
every day. Lu wants to learn to shoot too but Jack won't allow a kid to hold a gun. Whenever he
and Patrick accidentally see each other outside, they just ignore the other's presence. Lu is not
allowed to come in contact with Patrick, but Jack does tell her lots of stories about her mom, and
on Lu's birthday, he gifts her a box with all of Emma's belongings. Since he can't come in person,
Patrick plays the birthday song on his P.A. system, but the cake he made for Lu ends up eaten
by the dog. He is so mad at the fact he can't celebrate with Lu that after Jack goes to bed,
Patrick plays music really loudly to make it hard for his neighbor to sleep. Lu does sleep
through the noise, but she wakes later because of a nightmare and when she looks through the window,
she sees a terrifying monster near the fence. The next morning, Jack finds her hiding under the bed
and when he hears her story, he tells her it was just a nightmare. This isn't enough for Lu, who is
still scared, thus later she leaves her bunny at the hole in the fence so it can protect her home
from all the monsters, and when Patrick sees her, he realizes she must be the one who's been feeding
cookies to his pet. Patrick comes out to warn her not to give sweets to a dog because it isn't good
for his health, but when Jack sees this from the inside, he misunderstands the situation and
rushes outside to tell Patrick off. If Jack ever sees Patrick near Lu again or hears any barking,
he will shoot the dog. Afterward, Patrick goes to a warehouse to pick up some supplies,
including a doll he knew Lu wanted. Emma's grave is outside this building, and this reminds Patrick
of an argument he had with her here during which he accused her of cheating on him with Jack. His
reminiscing is suddenly interrupted when he comes across a dead animal on the floor, and following
its trail makes him discover there is a zombie in the building. Lu hadn't been inventing things:
zombies are back because they've evolved to be able to stand the cold. Patrick immediately
runs away with his dog and closes the door behind him before jumping on his snowmobile,
but driving at such high speed and keeping an eye out for the zombie causes him to crash against a
fallen tree. The zombie breaks down the door and reaches Patrick, however it is blind and doesn't
notice his presence. Back at home, Jack is finally teaching Lu how to fire a gun, and the sound gets
the zombie's attention. Patrick notices the zombie is going into town and gets back on
the snowmobile to drive back, using high speed to arrive at the same time and run over the zombie as
he tries to warn Jack to run away. Unfortunately the zombie recovers quickly and attacks Patrick,
biting him on the neck. Jack wants to shoot but he hesitates because he can't aim well
when Patrick and the zombie are moving so much, so it is the dog who comes to Patrick's rescue,
but the zombie ends up attacking him instead. Now that the monster is off Patrick, he shoots
and scares it away, but it's too late: the dog is dead, and Lu is mad at Jack for not reacting
sooner. After saying goodbye to his dog, Patrick cleans his wound with alcohol and thinks of using
his gun to end things. In the end he doesn't dare, but he remembers that when Emma got bitten,
they got rid of her arm to stop the infection. The memory shock makes him pass out, and he doesn't
wake up until the evening when he hears voices coming from the radio. Finally someone is replying
to his messages, and Patrick immediately tells this stranger about zombies coming back and biting
him. The voice points out that too much time has passed and Patrick should be a zombie by now,
meaning this newly evolved creature can't infect through its bite. As Patrick thinks of finding
the zombie to kill it, another voice cuts in and mentions this isn't the zombie's fault,
it's Jack's - it turns out these voices are in Patrick's head. In the morning, Jack has boarded
up all the windows thinking zombie Patrick may come after them, only to be shocked when he sees
him outside well and healthy. Lu's still offended because Jack didn't believe her when she saw the
zombie and didn't help Patrick and their dog, so to calm her down, he promises to pick up some
flowers for her mom's little altar since Lu can't do it anymore because Jack won't allow her to
leave the house now that they know the zombies are back. As soon as Jack goes outside, he finds the
doll Patrick has picked up for Lu, which must've fallen during the fight. Meanwhile Patrick has
been drinking a lot, and he keeps hearing the voices telling him to kill Jack because he has
everything he doesn't, and he shouldn't feel bad for this guy after letting Emma die. Back to Jack,
he finds flowers in an abandoned home with only dead people inside, and bringing them to
Lu makes her be nice to him again. She puts half of them near a picture of her mother,
then she puts a revolver in her pocket before sneaking outside to crawl through the fence hole
and leave the other half of the flowers on the dog's grave. Suddenly a zombie appears behind her,
and when Lu tries to shoot it, it simples hits her and makes her fall. Jack hears the commotion
and immediately runs out to help her, desperately jumping on the zombie and beating him up with his
bare fists. Then Jack goes to check on Lu, but it turns out the zombie isn't actually dead and
tries to attack again, luckily Patrick hears the noise too and comes out to shoot the beast just in
time. Jack passes out from the wounds the zombie inflicted on him and wakes up later in his bed
only to realize Lu is gone. He rushes outside and is shocked to find a zombie with no arms chained
to the ground. Patrick comes out as well and explains that this is the zombie Jack defeated,
it's still fine because the creatures have evolved to seal their own wounds too; Patrick has chained
it up to test this new healing power. But since they're also blind and can't infect humans
anymore, Patrick thinks this gives them a fighting chance. At that moment, Lu comes out of Patrick's
house and explains he's been watching over her after they took care of Jack's wounds. As Jack
drags Lu back into the house, Patrick returns to his own and finds that Lu left him a drawing
of all of them together. Moments later, Lu calls him through the walkie-talkie and invites him to
have dinner with them. Patrick is so happy about this that he shaves his beard and cuts his hair,
wanting to look friendly and approachable. When he finally comes over, Jack gives Patrick the doll in
order for him to gift it to Lu himself, and it makes the girl very happy. Dinner goes great,
and soon everyone is laughing at the anecdotes Patrick has of his own childhood. After Lu goes
to sleep, Patricks informs Jack that he's fixing his truck so they can leave because
he thinks more zombies will find them soon. Jack refuses because he thinks it is safe here,
causing Patrick to point out that Jack is too concentrated on surviving and has forgotten
how to really live. If Patrick is so sure about this, Jack wonders why he hasn't left on his own,
and Patrick explains he's staying for Lu, who is actually his daughter and not Jack's. Patrick is
grateful for the great job Jack has done with raising Lu and he's sure Emma would've thought
the same, but the mention of her pisses Jack off and makes him kick Patrick out. Afterward, Jack
can't help thinking about the day Emma died: Jack had found Patrick drunkenly saying he killed Emma,
this made Jack furious and he took Lu away from Patrick, telling him he wouldn't be Lu's father
anymore. That night, Lu has a nightmare about being left alone, so the next morning Jack agrees
for them to join Patrick and leave town. First they stop by the warehouse for supplies, and
Patrick can't help thinking of Emma again. That day when Patrick had been irrationally jealous of
Jack, he left Emma alone in the truck after their argument, and the zombies found her. Patrick never
killed her literally, but he felt responsible and the guilt pushed him to drink. After they gather
enough supplies, the group gets ready to leave again, but they come across a woman named Anne
standing in the snow. When they try to approach her, she begins panicking because she's in shock,
so the guys do their best to calm her down and take her back to town, their trip forgotten for
now. As soon as they tuck her in bed to warm her up, they discover Anne is pregnant. Hours
later when Anne is feeling better, she shares her story with everyone. When the outbreak happened,
she and her family shut themselves in their house, but after a year, they got tired of just surviving
and they left to find other survivors in order to truly live again. Among the group they joined,
there was a guy Anne fell in love with, but he never got to learn he was going to be a
father before they were attacked by the evolved zombies, leaving Anne as the only survivor. Their
conversation is suddenly interrupted when the chained zombie outside starts howling, making Anne
rush out of the house to shoot him because these howls are the way they have to call out to each
other. This proves to be true when more howling can be heard in the distance, indicating a horde
of zombies is coming. The group immediately goes back into the house and gets their weapons ready
to defend themselves. Lu is left in the basement for the sake of her safety, but it turns out there
is a zombie down there already. She remembers to stay quiet to avoid being noticed and comes up
with a quick plan: she throws her lantern into a trunk and the zombie goes after it when it
hears the noise, allowing Lu to lock the creature inside. Upstairs, the adults are having trouble
of their own: Anne and Patrick have to push some furniture against a door to keep zombies out while
Jack pushes back a different door to stop another creature from getting inside. He shoots the
creature as well, but he soon runs out of ammo and begins to wonder if he'll have to fight the zombie
hand-to-hand like it's happening to Patrick as well. Fortunately Anne comes up with an idea and
uses Patrick's P.A. system to play music really loudly, which hurts the zombies' sensitive ears.
At that moment Lu comes out of the basement, and after hearing about the monster there,
Patrick sends her to stay with the radio. This turns out to be an excellent idea because while
the adults continue to fight the zombies with the few bullets they have left, someone finally
contacts them through the radio and Lu gets to hear there's a colony of survivors in Spring
Falls. Suddenly, both the radio and the music die because the generator has run out of fuel, and it
is impossible to reach it to refill it because it's outside with the zombies. When Lu brings
the adults the news of the colony, Patrick opts for a sacrifice to allow the others to escape:
after kissing Lu goodbye, he rushes outside with a flare and a shotgun, shooting the last few
bullets and yelling to make all the zombies come after him. As soon as the others safely reach the
truck and drive away, Patrick throws the flare at the gasoline tanks to kill all the zombies in
a huge explosion. He dies too while thinking of Emma and the big belly she used to have before
giving birth to Lu. Jack, Anne, and Lu drive away from Harmony with no issues, and when they reach
a cliff outside the forest, they stop the truck so Lu can see a clear sunrise for the first time.