30 Days of Night follows the isolated town of Barrow, Alaska, a place that plunges into a month-long polar night every winter. As the final day of sunlight fades, most residents leave, but a small group chooses to stay behind, including Sheriff Eben Oleson and his estranged wife, Stella. Strange events begin to unfold—a series of unexplained vandalism cases, dead sled dogs, and a mysterious stranger who warns that something terrible is coming. Eben senses that these incidents are connected, but he cannot imagine the scale of the horror that is about to descend on the town.

When darkness fully settles, a clan of ancient vampires arrives, led by the ruthless Marlow. They strike with brutal precision, cutting power, destroying communication lines, and slaughtering the remaining townspeople. The vampires move through Barrow like a storm, turning the quiet settlement into a blood-soaked battleground. Eben desperately gathers survivors, trying to find shelter and a way to stay hidden as the vampires make it clear that no human will be left alive by the end of the thirty days.

The survivors hide in attics and abandoned buildings, whispering in fear as they watch the vampires hunt outside. Eben struggles with the weight of keeping everyone alive while confronting the broken relationship with Stella, who becomes both his emotional anchor and his equal in courage. Every moment is a fight between hope and despair, and the sound of footsteps or distant screams reminds them that death is never far away.

As the days pass, food dwindles, temperatures drop, and exhaustion grows. The vampires use psychological terror, setting traps and drawing people out with false hope. Eben’s brother, Jake, fights to stay strong despite immense fear, while other survivors slowly lose trust in one another. The town becomes a frozen graveyard, and Eben realizes that survival requires difficult choices and immense sacrifice.

Approaching the end of the thirty days, Eben discovers that conventional weapons cannot defeat the vampires. In a final act of desperation, he injects himself with vampire blood, transforming into a hybrid strong enough to challenge Marlow. The transformation is painful, but it gives him the power to fight on equal ground.

The climax brings Eben face-to-face with Marlow in a brutal confrontation that ends with the sheriff defeating the vampire leader. However, the victory comes at a heartbreaking cost. As the sun finally rises, Eben knows he cannot remain human and watches the dawn with Stella by his side before the sunlight destroys him. The film closes with a bittersweet sense of love, loss, and sacrifice under the endless Arctic sky.