In June 2004, a group of several film students travel to Bonville, Ontario, Canada to interview locals about the impact of deforestation on their lives for a documentary they call "Hard Pines", directed by the group leader, Reese. Steve, a local and uncle of the cameraman Brandon, gives them a hard time with the interview. Alain, another local, interrupts the interview asking Steve about the progress on Alain's new shed.
That night, the group and Steve sit around a campfire and tell stories. Kwekon, a member of the group and of native heritage, tells the story of the Windigo, a native legend. The legend explains that those who were forced to cannibalize humans were transformed into Windigos or were possessed by Windigos, creatures with elongated arms and legs, sharpened claws and teeth, and no eyes, that live in the forest and despise fire. Kwekon explains that his parents were killed by a Windigo when he was young while camping, and that it had attacked him, showing the group a large scar on his chest. Steve confirms that the Windigos are real.
The following day, the group goes to interview Alain. The interview does not go well, as Alain is pro-deforestation, but they convince him to lie by telling him that a television star he likes will see the film and is anti-deforestation. Alain gives the location of a clearing in the forest that could be used as the backdrop for their documentary. That night they visit another local, Tristan, who works for Steve, whose camper is located close to their campsite. They introduce themselves and head to the campsite for the night.
The following day, they do some shooting in a canoe, with Selina as the actress explaining the dangers of polluting waterways. They visit Tristan again that night, get drunk and play cards. When Tristan loses, he furiously storms out of his camper into the night. The rest of the crew leaves for the campsite. After several hours of fooling around, they go to sleep. They hear Selina awake and leave her tent, and they drunkenly follow her as she walks into the forest. When she disappears into the night, the return to the tents and sleep. When they awake they have no memory of this and assume she is missing.
The crew splits up the next day in the forest. Brandon meets Steve in the woods, burying tapes in the dirt. Claiming the camera is off, Brandon holds a conversation with Steve, who threatens him to remain quiet and to not ask questions. When Brandon pushes his luck, Steve tries to attack him, but Brandon flees into the trees. After seeing the Windigo in the woods and being lost, he eventually locates the other half of the group and tells them that he saw what took Selina, quickly redacting it and claiming it was a joke.
Brandon heads back with them, and that night something strange happens. The tape shows Brandon seemingly attacking the person with the camera and leading two people into the forest. Brendon awakes with the camera in the forest. He finds skeletons of small creatures around him, and wanders through the wilderness for several hours. He eventually comes to a field, and finds the body of Selina. A truck approaches, and Steve gets out. When Brendon asks him what he's doing, Steve replies that he's there to kill Brandon for his murders and grabs a gun from his truck. Brandon runs, and sees Alain in the field, telling him which direction to go. Alain attacks Steve and knocks him unconscious. He then forces Brendon to come with him to his home, where he ties Brendon to a chair and tells him that he's being tormented by people on his property, leaving mud on his lawn during droughts leading to him being fined for water usage when he has not, and various other problems. He believes it to be Steve, and intends to extract information out of Brandon.
Alain goes to his kitchen and begins to find tools to torture Brandon with, when his bathroom door all of a sudden opens by itself. When Alain enters the bathroom to investigate, the door shuts and Alain is killed. Soon, the film crew enters the house and unties Brandon. They see blood seeping from under the bathroom door and force it open- at the same time a Windigo appears in the window briefly. When one of the actors, Dean, enters the bathroom, the door closes. They see a Windigo peering from around the corner and fire a shotgun at it, to no noticeable effect. When they force the door open, Dean appears as a Windigo and is shot. They run panicked through the house outside to the truck, trying to bring with them the tapes that are scattered across the area as group of faceless people shamble towards them in a zombie-like fashion. As they hold off the people, Brandon tries to leave without them with all the tapes in Reese's car, when Reese jumps through the passenger window and stops him. In the frantic chaos, the Windigo/Slender Man is weakened by fire and possesses Brandon's body; Reese and Brandon fight, with Brandon now sporting a tentacle from his arm. Reese knocks Brendon unconscious, and they load him into the back of the truck. When he awakes, he once again tries to fight, and is thrown off the back of the moving truck.
The video explains how there was no evidence and no survivors left at Bonville, except Brandon. Brandon is seen being interrogated by the government, being asked his name by frustrated agents. Brandon denies any involvement in the incident. Suddenly, something off screen kills the agents as Brandon begins puking up blood and laughing. In the distorted video, it can be seen that Brandon has transformed into a Windigo. It is explained that by the time security got to the room, the agents were dead and Brandon was gone.
The Windigo and Slender Man
In Algonquian legends, Windigos are spirits that humans could transform into or be possessed by through cannibalism. They were often linked with famine, starvation, and emaciation. Their appearance was generally described as extremely starved and emaciated, being skin pulled tight over a skeleton.
The zombies attacking the group are likely puppets, an extreme version of proxies whereby the Slender Man controls the victim completely, or possesses them.
What can not be explained is how there are seemingly multiple Windigos, when many assume there is only one Slender Man. This does not necessarily conflict with canon, as there has never been said or proven to be only one Slender Man. Alternately, Quantum Theory could be worked to give the Slender Man the ability to manipulate physical beings to sort of 'reincarnate' itself or reform itself out of their flesh. The Tulpa Effect would make sense, by allowing the victims to view the threat how they perceive it, and would account for how there are seemingly multiple Slender Men (multiple Tulpas), and for how Dean could be misinterpreted as a Slender Man. Also most legends of the Windigo mostly describe the creature as deer like, which is possible but hard to mistake for Slender Man. The same is possible for the alternate that someone would mistake Slender Man for a Windigo but is still an unlikely scenario.
Alternatively, Windigo may not abide by conventional Slender Man canon and mythology, and may indeed go by its own rules.