Christopher Robin escapes the Hundred Acre Wood, haunted by the horrifying actions of Winnie-the-Pooh and Piglet, who have embarked on a brutal killing spree. Seeking solace, he returns to his childhood town of Ashdown, only to find himself embroiled in a nightmare of his own making. The gruesome discovery of the remains of Maria and her friends in the woods leads the community to label him the culprit behind the so-called "Hundred Acre Massacre." This shocking event spirals Christopher's life into chaos, tarnishing his reputation within the town and transforming him into an outcast.
Unable to escape the haunting memories, Christopher is plagued by nightmares of Pooh. In an effort to confront his childhood trauma, particularly the abduction of his twin brother Billy, he visits his hypnotherapist, Samantha. Meanwhile, in the woods, Pooh and Piglet, along with their companions Tigger and Owl, find themselves in hiding as some townspeople begin to believe Christopher's version of events. The tension escalates when Pooh and Piglet, driven by bloodlust, brutally murder three unsuspecting university students in a parked RV. Convincing Pooh that they can no longer remain dormant, Owl devises a plan to instigate a massacre in Ashdown.
As the situation unravels, Christopher loses his job as a doctor and continues intensive hypnotherapy with Samantha to unravel the tangled truths of his past. He eventually encounters Cavendish, the hospital janitor, who reveals a horrific secret: he was once coerced into kidnapping children for a mad scientist, Dr. Arthur Gallup, whose experiments resulted in them becoming grotesque hybrids buried in the very woods Christopher once viewed as innocent. The revelation that Billy was among the victims, resurrected as Pooh, sends Cavendish spiraling into despair, leading him to take his own life.
Determined to warn Ashdown of the lurking danger, Christopher's cries for help are met with scorn and disbelief. Meanwhile, Pooh, Tigger, and Owl unleash terror upon the town, mercilessly slaying residents, including Christopher's dearest friend Finn. In a horrifying turn of events, Pooh brutally murders Christopher's parents, Alan and Daphne, and snatches away his younger sister, Helen, affectionately known as Bunny. Christopher's girlfriend, Lexy, narrowly escapes a deadly encounter.
The horrifying climax unfolds at a rave party in a warehouse, where the creatures go on a killing spree, leaving a trail of devastation in their wake. In the midst of this chaos, Christopher and Lexy manage to eliminate Tigger, only to discover that Bunny remains captive. They resolve to confront Pooh back in the Hundred Acre Wood, but the encounter takes a dark twist as Pooh overpowers them. However, when Christopher calls him by his true name, Billy, the memories of his youth flood back, but not without accusations of betrayal for abandoning the creatures, thus leading to dire consequences in the past.
In a heart-wrenching confrontation, Christopher is compelled to take Pooh's life with an axe before finally reuniting with Lexy and Bunny. As the police investigate the gruesome events, footage of the nocturnal rampage exposes the truth, leading to Christopher’s exoneration. In a chilling concluding scene, Owl, the last survivor of the group, collects the remains of Pooh, Piglet, and Tigger, vowing to resurrect them with the aid of some sinister allies. The credits roll with eerie sketches featuring beloved characters from classic tales like Bambi, Peter Pan, and Pinocchio, leaving an unsettling suggestion that magic and horror are intertwined in ways unimagined.
