Plot
Narrowly having survived Winnie-the-Pooh's and Piglet's killing spree, Christopher Robin flees from the Hundred Acre Wood and comes back to his childhood town of Ashdown to seek help; the corpses of Maria and her friends are recovered from the woods, but Christopher is believed to be responsible.
The incident is dubbed the "Hundred Acre Massacre", and a film adaptation based on the murders is released, damaging Christopher's reputation in Ashdown. Only a few people believe Christopher's story, including his childhood friends Lexy, Finn, and Aaron, his parents Alan and Daphne, and his younger sister Bunny. Now an outcast, Christopher has nightmares about Pooh and goes to his hypnotherapist Mary Darling to deal with a trauma in which his twin brother Billy was kidnapped many years ago during their birthday party, and was never seen again.
Meanwhile, in the Hundred Acre Wood, Pooh and Piglet are forced to hide with fellow creatures Tigger and Owl when their home is burned down. Having slaughtered 3 of the university students in a recreational vehicle, Owl tries to convince Pooh to attack Ashdown instead of waiting for more people to come to the woods. Some hunters, among them Aaron, ambush the creatures and shoot Piglet in the head as revenge for the deaths of Maria's group. Pooh murders them in retaliation and reconsiders Owl's proposal, but Aaron survives and returns to Ashdown.
Following the town's negative backlash, Christopher gets fired from the hospital and then comes back with Mary to undergo further hypnotherapy. When Aaron arrives at the local hospital for treatment, Christopher suspects the attack was done by Pooh, which is confirmed when he asks Aaron what happened. He also encounters hospital janitor Cavendish, whom he recognises as the man who kidnapped Billy, and confronts him in his house. Cavendish reveals that he worked for Dr. Arthur Gallup, a scientist who employed him to kidnap children—among them Billy—around Ashdown for experiments with animal genes in exchange for settling his debts. The children became animal-human hybrids with enhanced healing factors, whom Gallup killed and buried in the Hundred Acre Wood. Cavendish subsequently killed Gallup and learnt the children resurrected/dug themselves out of their graves. Cavendish burns the last evidence linking him to Gallup and kills himself out of guilt.
As night falls, Pooh, Tigger, and Owl embark on a rampage throughout Ashdown and murder several residents on the way, including Finn. Pooh personally murders Alan and Daphne and attacks Lexy while she is babysitting, but she survives the ordeal. The creatures then arrive at a rave party in an abandoned warehouse and slaughter all the partygoers. Christopher rushes to the warehouse, where he shoots Tigger, and learns Bunny was kidnapped. He returns to the Hundred Acre Wood and fights Pooh, who easily subdues him as they stumble across Billy's own grave. Christopher calls Pooh—actually known as Billy—by his real name. Lexy intervenes and stalls Pooh long enough for Christopher to murder him with an axe. Video footage of Pooh is passed to the police, who found Bunny in her room unharmed, and Christopher is subsequently cleared of any wrongdoing. Christopher and Bunny are reunited and escorted home by the police.
In a mid-credits scene, Owl and Tigger, having survived, recover the corpses of Pooh and Piglet, with Owl swearing to find a way to bring them back and that they will get their revenge on Christopher, once and for all.
