Plot
As the town of Barrow, Alaska prepares for the annual month-long polar night, a stranger arrives from a large icebreaker ship that is hidden some ways off and walks into town. Evading detection, he begins sabotaging means of communication and transportation by stealing/burning all of the satellite phones, destroying a helicopter, and killing all of the sled dogs.
Barrow's sheriff, Eben Oleson, is busy investigating the seemingly separate instances of sabotage with his deputy, Billy Kitka, when he learns that his estranged wife, Stella, is in town on her rounds as a fire marshal.
She tells him that she needs a ride to catch the last plane out, or she will be forced to stay for the month. Eben has another urgent call that he must attend, but sends Billy to give Stella a ride. Billy, however, deliberately takes too long, and Stella misses her flight.
As darkness falls, things around town begin to rapidly escalate, and Eben runs into Stella when she assists him in corralling the stranger, who he finds harassing the waitress, Lucy, at the local diner.
After taking him back to the police station and locking him in a holding cell, the phone lines and internet go down. Eben heads out alone to check on Gus, the technician in charge of Barrow’s telecommunications station.
Unbeknownst to anyone but the stranger, a band of vampires arrives from the ship, prepared for an attack.
After killing Gus and destroying the equipment, they leave his head on a spike outside the building. When Eben shows up and sees this, he rushes back to town, stopping only to tell some concerned citizens that they should return home, lock their doors, load their firearms, and wait for more information, or meet at the diner if they don't have generators.
As he returns to the police station, still unaware of what is coming, the slaughter of the townspeople commences, beginning with Ellie Riis, who is dragged out of her house through her kitchen window. Her husband, John, is injured and left for dead while trying to save her.
Eben arrives back just in time to stop the stranger from strangling his younger brother, Jake, and demands to know who killed Gus. The man, enraged by being shot, simply tells him, "You're all dead men! I don't talk to dead men!"
With no information, Eben decides to go out and search for whoever else is new in town, planning on doing a sweep with Stella and Billy. While Stella is driving, Eben spots movement and tells her to stop the truck. They both step out, and Stella uses binoculars to see something ahead in the road, frantically telling Eben to get back in the truck before trying to speed away. One of the vampires catches the vehicle and jumps on, but they escape when Eben shoots him through the roof, and he falls off. They then hear Eben's grandmother, Helen, over the radio, crying for help before the line goes dead.
When they arrive back at the police station, Jake and Helen are gone, leaving nothing but a large amount of blood and the stranger, who is still handcuffed in the cell. Eben is distraught over the thought that his brother is dead, and is almost convinced by the stranger to kill him, until Stella snaps him out of it.
At the diner, Eben and Stella find Jake, along with several other survivors who have evaded the vampires, and they decide to take shelter in a boarded-up house with a hidden attic. As the group prepares to move to the attic hideout, Eben separates from them to try and go collect weapons, and Stella joins him. Before they can accomplish anything, however, their SUV is ambushed by the band of vampires, who flip the vehicle over and drag them out. Beau Brower, the town snowplow operator, arrives, using his plow to kill some of the vampires and drive Eben and Stella to safety before joining them at the house where they were supposed to meet the others.
After a large-scale massacre in the streets, Marlow, the leader of the vampires, enters the police station holding cell, where he finds the stranger, who believes the vampires will "turn" him as a reward for his help. However, Marlow shows disapproval at how trusting and stupid humans are, and snaps his neck instead.
As time passes in the attic, things begin to get tense. With limited supplies and after seeing that the vampires are raiding nearby houses in search of survivors, the group decides that they cannot remain there indefinitely, and plan to use the next snowstorm as cover to move.
On day seven, the vampires use a survivor as bait in an attempt to lure out any others in hiding, allowing her to walk through the streets calling out for help, while vampires shadow her from the rooftops. Eben sees the trap, but goes out to save her anyway. After realizing that he's too late for her, he instead takes the opportunity to save another resident he finds hiding underneath a house, John Riis. However, Eben is horrified to see that John has been turned, and reluctantly kills him in self-defense, returning to the house in the midst of an asthma attack before telling Stella and Beau that "John Riis became one of them".
Marlow and his mate, Iris, find John's body, and Marlow, upon seeing that he had been turned, looks disquieted.
While Eben is resting and Stella is on watch, Isaac Bulosan, an elderly man with dementia, leaves the attic. Stella wakes up and tries to stop him, but he tricks her and his son, Wilson, climbing out of the bathroom window. Discovering his father is gone, Wilson frantically rushes to find him, knocking Stella down as she tries to stop him. He runs out into the open, leaving the door open. Eben is woken by the impact of Stella hitting her head and comes down to find her stunned on the floor. She tells him what happened, and they hear something approaching. A particularly vicious vampire, Arvin, enters the house and almost finds them hiding in the bathroom, but he hears Wilson yelling outside and leaves to find him. Shortly after, Stella and Eben hear Wilson's screams as he is caught and killed. Stella blames herself for Wilson's death, saying that she should have fought harder.
Sometime later, the blizzard the survivors have been waiting for hits the town, causing a whiteout. Under the cover of the storm, the group goes to the general store for supplies, but are attacked by a vampire child, whom Jake has to kill, and end up stranded there after the blizzard abruptly ends.
On day eighteen, the group decides they must try to head for the police station even though another whiteout hasn't happened. Carter, the manager of the utilidor, a power and sewage treatment station, suggests that they could make it if someone creates a diversion. Eben takes it upon himself and lures the vampires to his grandmother's house, where there are ultraviolet grow lights, and uses one to burn Iris when she tries to rush in after him. Severely burned by the light, Iris is on the ground, thrashing in pain and whimpering, which forces Marlow to mercy-kill her.
Eben, having fled the house and escaped immediate capture, radios Stella that there are too many vampires out and he can't get away cleanly. Hearing that, Beau steps up to help, taking weapons and dynamite in a back loader tractor equipped with a chain trencher and going out to kill as many vampires as possible. When he crashes into a building, Beau attempts a suicide bombing to kill the remaining vampires. However, Beau and the vampires survive the explosion, and Marlow crushes his skull as he tries to escape the flames.
Eben returns to the station alone and informs the others that Beau didn't make it, at which point Carter stands up and reveals that he was scratched at the store and is changing. He admits that his wife and kids never came up to join him because they were killed by a drunk driver, and asks Eben to kill him so he can go be with them, which Eben does. Then, seeing from a window that Billy is signaling them with a flashlight from his home across the street, Stella and Eben go to get Billy and bring him back to the station.
The trio returns to find the others have gone. They guess that they have made for the utilidor, since that still has power, and head over there. On the way, Stella splits from the group to save a young girl, Gail Robbins, who she sees wandering down the road covered in blood after her family was slaughtered. Before they can hide, however, they are spotted by a vampire who was pursuing the girl, and Eben comes out to distract the vampire so that they can get away. Billy stumbles out after him and runs off, forcing Eben to flee too.
Eben makes it to the utilidor to find the group, but not Stella or Gail. Billy arrives shortly after, and they are all attacked by the vampire Arvin, who followed him there. Billy is bitten, but manages to kill Arvin by tackling him into the industrial grinder as he attacks Eben. Eben is then forced to kill Billy when he starts to turn.
At some point, Stella manages to raise Eben on a radio, informing him that she and Gail are alive, but trapped under a wrecked truck out on the main road. Jake identifies the vehicle, as they can see it out a window. Confirming that the vampires are everywhere, Eben tells Stella to stay put and turn off her radio before they hear her.
As the month ends, and the sunrise approaches, Marlow and the vampires plan to cut the oil pipeline line running through the town and ignite everything, using fire to destroy any evidence of their existence.
Eben and the survivors in the utilidor see oil filling the streets. Realizing Stella and Gail are trapped in the fire zone and that he cannot beat the vampires in his current state, Eben injects himself with Billy's blood. Newly turned vampire Eben emerges, planning to confront Marlow in order to give Stella and Gail an opportunity to run for safety. Although losing most of the fight, Eben manages to kill Marlow, leaving the vampires without a leader and causing those remaining to flee.
With the attack over, Eben and Stella, now among the town's only survivors, decide to spend the last of their time together watching the sunrise. As the light hits them, Eben's body burns to ash in Stella's arms.
