The film kicks off with Jenny Tate and Becky Morton, who are enjoying a leisurely day at the pier when they decide to consult a fortune teller named Zela. Zela's ominous prediction hints at a terrible fate awaiting them, but the pair dismiss her warnings with laughter and walk away. Their carefree attitude quickly changes when Becky realizes that Jenny has vanished, sending her into a frantic search on the pier where she drives.
Later, we find Jimmy and his sister Ellie having a fateful night drive, where they accidentally hit an animal, followed by a collision with another car. In a horrifying turn of events, they attempt to rescue the driver, only to witness Becky being suddenly dragged away and devoured by an unseen creature. Both siblings suffer slashing attacks from this monstrous entity, and Jimmy grows increasingly convinced that they are dealing with a werewolf, despite being met with skepticism from those around him.
As events unfold, Jimmy and Ellie begin to experience bizarre wolf-like behaviors, such as craving raw meat and exhibiting heightened instincts - though Ellie maintains her denial, seemingly proving her point through a touch of a silver picture frame without consequence. Yet, Jimmy's transformation becomes evident as he gains remarkable strength, easily overcoming bullies like Bo, who attempts to compel him to join the wrestling team.
Tragedy strikes when Jenny is brutally murdered in a parking garage, confirming Zela's grim prediction. As the situation spirals out of control, Ellie starts to accept the notion of a werewolf, a realization that hits home when Jimmy suffers a burn from a silver cake server, revealing his fear holds justification. The siblings, along with Bo, race to confront the looming danger as Ellie discovers her boyfriend, Jake, harbors his own werewolf secret.
Conflict arises when a new werewolf emerges, revealed to be Joanie, a vindictive publicist connected to Jake's past who seeks revenge on all his romantic interests. She clashes with Ellie and Jimmy, leading to a fierce battle when Joanie transforms into her monstrous form. Despite her ferocity, law enforcement intervenes, resulting in fatal shots aimed at Joanie. For a werewolf to be truly vanquished, it must be decapitated; as she rises once more, a cop takes the decisive shot, finally ending her threat.
In a jarring twist, a dog bites Jimmy, setting off a chain reaction of chaos in their already-destroyed home, revealing that now their pet has become a werewolf. Amidst the turmoil, Jake reappears, disclosing that he is responsible for biting both Jimmy and Ellie, wishing for Ellie to join him in eternal life after dispatching her brother. The ensuing confrontation reveals that while Ellie struggles with her werewolf nature, Jake has mastered his, granting him the upper hand.
However, chaos breaks loose when Jimmy leaps into action, biting Jake to deliver a crucial distraction, allowing Ellie to inflict a severe wound with the silver cake server. In a climactic duel, Ellie ultimately decapitates Jake with a shovel, liberating herself, Jimmy, and their dog from the werewolf curse. The aftermath finds Brooke, a girl Jimmy likes, and Bo visiting, marking new beginnings and friendships as they all embrace the next chapter in their lives, leaving Ellie to ponder the wreckage of their once safe home.
