Scott Cowley and his guide trek through the Cameroon jungle when a radio message from Charlie Cowley cuts in, claiming his own guide has vanished. The transmission is shredded by terrifying, animal-like sounds, and the two hunters press on to offer help, only to become targets themselves. [Charlie Cowley] later discovers [Scott Cowley] fatally wounded, a grim hint of the danger that started years before.
Seven years slip by as the story centers on Derek Cowley, Charlie’s nephew, who lives with his mother Gwen Cowley and his emotionally abusive stepfather, Mitchell Toblat. Derek schemes to use Mitch’s cabin for a weekend party to impress his classmates, while Mitch is away on a work trip. That night, the secluded retreat becomes a killing field as a brutal werewolf attack slaughters four partygoers, leaving Derek and his ally, Samantha 'Sam' Marche, as the only survivors.
The immediate aftermath is cold and muttered; the teens pretend they didn’t see the attacker, and Mitch treats Derek like the architect of the tragedy. Yet Derek and Sam grow suspicious, realizing Mitch could be the killer. When [Charlie Cowley] drops by for a visit, the adults are stunned to hear him acknowledge the possibility that the monster is human, not supernatural per se. He believes the Cameroon case pointed to Mitch, drawn by a fixation on Gwen, but he cautions that without DNA evidence, accusations carry grave consequences. He keeps a hair sample as a potential link.
As the tension inside the house escalates, Charlie reconnects with Gwen, and a romance blooms between Sam and Derek, offering a fragile beacon of hope amid danger. The situation intensifies when Mitch catches Sam snooping and forces her into a sexual act to obtain a DNA sample, a cruel move that strains Derek’s trust in her. Meanwhile, Mitch has been shadowing Charlie, and he eventually steals a package addressed to Charlie, uncovering the DNA test results that could finally pin him to the killings.
In a brutal turn, Mitch abducts Charlie and reveals a chilling truth: he can shapeshift at will, without relying on the full moon. He dispatches Charlie in a sudden, merciless confrontation. Derek unearths the DNA report and confronts Mitch, while Gwen makes the difficult decision to leave the abusive man behind. Mitch’s plan shifts to Sam as he kidnaps her and forces Derek to meet him at the cabin alone.
Derek arrives to find a new group of youths exploring the site, now infamous for the massacre. Mitch transforms and methodically targets them, leaving only Derek and Sam standing. The two fight back with makeshift weapons, including silver implements, and set Mitch ablaze along with the cabin. They barely escape the blaze, sharing a relieved embrace, even as Mitch lingers long enough to launch a final attack on Derek. With his death, Mitch admits the curse now belongs to Derek, who is steadied by Sam’s steadfast promise to stand by him no matter what happens. They drive away together on Sam’s moped, a small glimmer of normalcy in a nightmarish saga.
In a post-credits moment, the antagonist’s fate lingers as Mitch moves his fingers slightly, leaving a last eerie hint of the danger that remains.
