A horrific encounter with a wendigo leads to tragedy when Kenny Glass is killed and Frank Weaver, played by Scott Haze, is severely mauled while they engage in meth production in an abandoned coalmine. The monstrous bite leaves Frank on a slow path towards becoming a wendigo himself. In a desperate effort to save his father and shield his younger brother Aiden from danger, Lucas Weaver, portrayed by Jeremy T. Thomas, takes the extreme step of confining Frank within their isolated home.
Years prior, Julia Meadows, a recovering alcoholic portrayed by Keri Russell, returns to Cispus Falls to start anew as a schoolteacher after fleeing an abusive upbringing. Moving in with her brother Paul, the town’s sheriff, played by Jesse Plemons, reignites old conflicts tied to their troubled pasts, particularly Julia's guilt over leaving Paul behind.
Julia becomes increasingly concerned for Lucas when she sees his unsettling drawings and hears his troubling tale about a family of bears transforming into monsters. Her instinct to investigate his situation deepens after a shocking discovery: while hiking, former sheriff Warren Stokes, portrayed by Graham Greene, stumbles upon a dismembered part of Kenny's corpse. His findings, which include native wards hanging in the mine, heighten the unsettling atmosphere surrounding Lucas's home life.
When Julia approaches the school principal Ellen Booth, played by Amy Madigan, about Lucas's drawings, she reluctantly agrees to visit the Weaver house. Tragically, Ellen's well-meaning attempt to check on the boys ends with her brutal murder at Frank’s hands as the wendigo violently erupts from his body.
As tensions rise, Clint Owens, a school bully, finds himself ruthlessly attacked by the wendigo, who is now Frank. Lucas returns home only to discover that Aiden has gone missing and the horrific scene of Ellen's mangled body sprawled across the floor.
Desperate to uncover the truth, Julia attempts to persuade Paul that Ellen and Clint’s disappearances are linked to Frank. However, their brief investigation yields no solid evidence. Determined, Julia ventures back to the Weaver residence, where she discovers Ellen's body, prompting Paul and the police to investigate and unearth the remnants of Frank's human form.
After Lucas is hospitalized for malnutrition and abuse, disputes arise between Julia and Paul regarding her urge to take custody of him. Julia, with Paul’s reluctant support, seeks insight from Stokes, who reveals the ancient lore surrounding the wendigo curse and the darkness that ensued from cannibalistic rituals. While Paul dismisses these supernatural accounts, Julia navigates the complexity of Lucas's claims about his father, insisting that Frank has merely been transformed and that he will come for them.
Chaos ensues when Daniel LeCroy, played by Rory Cochrane, is killed while investigating strange noises, leaving Paul to confront the monster as Julia strives to rescue Lucas and Aiden. In a high-stakes showdown, Julia confronts the wendigo and, motivated by her desire to save the children, ultimately aids Lucas in dispatching the creature, stealing its cursed heart in the process.
As tragedy continues to unfold, Julia witnesses Aiden’s horrifying transformation into a wendigo and is forced to confront the heartbreaking reality that saving him may no longer be possible. In a moment filled with emotion, she embraces Aiden before making the unimaginable decision to end his life to prevent further horror.
With the ordeal behind them, Julia and Paul reluctantly agree to care for Lucas, yet Paul is left unsettled, fearing the lingering curse he might carry himself after a troubling health scare. The weight of their trauma and the haunting dread of what lies ahead remains palpable as they step into an uncertain future.
