Mila and her sisters live with their brother Oskar in a small forest cabin in the snow. One night, a fur-clad stranger arrives seeking shelter for himself and his men. But by the next morning, they've gone, taking Oskar with them. Fearful for his safety, Mila and her sisters set out to bring Oskar back - even if it means going north, crossing wild and frozen lands to find a way past an eternal winter.