A married couple with two young girls decide to split up. Well, sort of: they will stay in their house, but take turns living with the girls. One week they have the girls and live upstairs, one week they live in the basement.

Two days before Christmas, while Sweden is paralyzed by a heavy snowstorm, five-week-old baby Lukas inexplicably disappears from his home. Experienced police officer Alice thinks that something is not right in the parents' stories.