PARK CITY, UTAH Jan. 24 (UPI) -- The Ugly Stepsister , which premiered Thursday at the Sundance Film Festival, embraces the darkness of the original Cinderella fairy tale. The Norwegian film ramps up the most disturbing elements of the Brothers Grimm version of the story, with the resources of modern cinema. Lea Myren plays Elvira, the older sister of Flo Fagerli's Alma. Their mother, Rebekka (Ane Dahl Torp), marries Agnes' (Thea Sofie Loch Næss) father but is widowed when he dies shortly after