Finn Wheeler, a dedicated forest ranger, arrives in the small town of Beaverfield to oversee a contentious pipeline project proposed by the businessman Sam Parker. Upon his arrival, he quickly forms a connection with the town's mail carrier, Cecily Moore, and meets a diverse group of residents, including the troubled couple Trisha Anderton and Pete Anderton, affluent duo Devon Wolfson and Joaquim Wolfson, and the local workers Gwen and Marcus. One particular resident, the reclusive Emerson Flint, adds to the town's eccentricity.
As darkness looms, a powerful blizzard strikes, plunging Beaverfield into chaos by cutting off power. The townsfolk, seeking shelter, gather at a lodge owned by Jeanine Sherman. Just as the power fails, tragedy strikes when Trisha's dog is brutally killed by an unidentified attacker, heightening the already tense situation. The mystery deepens when Finn discovers that all the town's generators have been tampered with, and the body of Jeanine's missing husband, Dave, is found hidden beneath the lodge's porch.
In a desperate attempt to secure safety, the residents barricade themselves in, but the horror escalates when Pete suffers a violent attack, losing a hand to the same shadowy figure. Environmental advocate Dr. Ellis, who opposes the pipeline, deduces that the threat is a werewolf living among them. Her shocking revelation takes a dark turn when she dies unexpectedly in front of Parker, who claims it was suicide, sowing further discord.
With the group fractured, most residents abandon the lodge, leaving only Finn and Cecily. As mistrust and paranoia seep through Beaverfield, the community begins to turn on one another. The specter of death looms larger as the existing tensions lead to murderous acts. In a climactic struggle, Parker accuses Finn of being the werewolf due to his history with previous attacks. Finn disputes this, revealing Parker’s manipulations intended to secure approval for the pipeline. Just when Parker seems to have the upper hand, Joaquim emerges as a hero, taking Parker down in his final moments.
While Finn and Cecily recover at the town's bar, he uncovers secrets from the past, discovering that Dave was the former mail carrier. Upon finding his undelivered packages, a chilling realization dawns on him: Cecily is the werewolf. When confronted, Cecily confesses to turning the town against itself to make feeding on them easier, admitting her unwillingness to hunt for food. In a terrifying showdown, she transforms and attempts to kill Finn, but with the assistance of Emerson, Finn fights back. In a final act of vengeance, Jeanine finishes Cecily off with a crossbow, resolving the haunting tragedy that has engulfed Beaverfield.
