Reluctantly, 17-year-old Gretchen (Hunter Schafer) leaves her American home to live with her father (Márton Csókás), who has just moved into a resort in the German Alps with his new family. Arriving at their future residence, they are greeted by Mr. König (Dan Stevens), her father's boss, who takes an inexplicable interest in Gretchen's mute half-sister Alma (Mila Lieu). Something doesn't seem right in this tranquil vacation paradise. Gretchen is plagued by strange noises and bloody visions until she discovers a shocking secret that also concerns her own family.
