The opening scene takes place in 1989 in Norway, with a half-naked boy running through the woods and across a road. This causes a truck to swerve and hit a parked car, killing the couple inside. Unfortunately their son was outside, taking a pee, and witnesses the whole thing. This is Peter.
Then, in present day, a guy named Kai returns to his home town after twenty years, to make arrangements for his mother's funeral. He seems very reluctant to go--but when he sees her body he wants to make sure she is indeed dead so he breaks her finger. He's satisfied when she doesn't react to this. Then, he goes off to revisit his old house, where he lived before taken into protective custody and raised in foster homes. He goes from room to room and there's flashbacks of some memories. One of the rooms has this huge pile of dolls all wrapped up like mummies. It seems that he's the kid we say at the beginning of the film, running through the woods. He gets creeped out at the house, especially by this bouncing red ball, so he checks himself into a local motel. There, he gets a phone call--and it's coming from the house--so he drives back there. At the same there's a young couple who are exploring the house, thinking it abandoned, and he watches them for a while--until they are hunted down by some other guy.
Kai is befriended by a local police woman, Sara, from the beginning, and she's investigating the couple's disappearance. Other police suspect Kai may have something to do with it but she's somewhat protective of him, knowing what he went through as a child and how that probably affected him. When they are exploring the house again he shows her a hidden room down in the basement, where he was imprisoned while his mother tortured him.
For the first hour we're not really sure if some of the things are happening in his mind or if there really is another person. He explains to Sara that it may be Peter, who was presumed to have drowned in the nearby falls and river. He thinks Peter may have been captured by his mother and imprisoned in that room, like he was, only for his entire life.
This is a low-key horror movie, rather TWIN-PEAKish.