Set against a chilling winter backdrop in a snow-covered forest during the uncertain medieval times, Valerie (played by Amanda Seyfried) is a young woman residing in the remote village of Daggerhorn. Deeply in love with the woodcutter Peter (Shiloh Fernandez), her future becomes complicated when her parents, Cesaire (Billy Burke) and Suzette (Virginia Madsen), arrange for her to marry wealthy blacksmith Adrian Lazar (Michael Shanks) and his son Henry (Max Irons). They hope that this union will elevate their family's status and provide a life of comfort.
As the couple schemes to escape their oppressive fate, tragedy strikes: the village is again stalked by a menacing werewolf. The discovery of Lucy, Valerie's older sister, among the haystacks after a brutal attack sends shockwaves through the community. The townspeople are aware of the tradition—a monthly sacrifice to the beast in hopes of keeping it at bay—but Lucy's venture into the woods reveals the depth of betrayal and love, as she had hoped to confront the engagement meant for Valerie, with whom she was envious.
In a dramatic turn, Adrian, Henry, Peter, and the other men venture into the woods, risking their lives to confront the wolf in its mountain cave. Although they manage to slay the beast, they return with the head of a common gray wolf, leading to a community celebration that is abruptly halted by the arrival of the notorious witch hunter, Father Solomon (Gary Oldman). He informs them that they have not killed the true werewolf, as it could have reverted to its human form if they had slain it correctly. His dire warnings hint at the effects of a forthcoming blood moon, under which those bitten will transform.
The town's merriment shifts to horror as the real wolf launches an attack, killing several attendees. Valerie and her friend Roxanne (Shauna Kain) find themselves cornered but are saved by a surprising connection: Valerie realizes she can understand the wolf, which leads to a shocking exchange where it suggests they escape together as equals.
Valerie's world spirals further when her family dynamics unravel—her mother confesses her affair with Adrian, revealing secrets that link Lucy and Henry as half-siblings, thus complicating her already strained ties. As chaos ensues and further bloodshed occurs, Father Solomon imprisons those he believes are connected to the wolf in a misguided attempt to subdue the supernatural mystery.
With the town enveloped in fear, Valerie discovers that friendship sometimes takes precedence over family loyalty as she navigates the turbulent events, ultimately leading to a dramatic showdown against the true nature of her lineage. When she learns that her father, Cesaire, is the wolf, it ignites a fierce battle for her identity and future.
In a heart-stopping climax, Peter arrives just in time to save Valerie from her father's dark intentions, revealing a depth of courage amidst the horror. Cesaire’s demise occurs at Valerie's hands, but not without cost, as she and Peter grapple with the reality of their grim inheritance—the wolf's legacy.
Despite the horrors they have faced, Valerie embraces her decision and opts to remain in her grandmother's house, memorializing the loss and acceptance of her family’s past as they attempt to build a future free from the cycle of darkness. In a poignant closing, she is reunited with Peter, who has grappled with his own transformation, hinting at the complex but enduring bond they share. Their silhouette against the snow-capped mountains highlights a love that both endures and evolves, standing resilient against the shadows of their history.
