At 17, Gretchen is uprooted from her American life to join her father and his new family at a resort in the German Alps. Her father’s employer, Mr. König, unsettlingly fixates on Gretchen’s mute half-sister, Alma. As they settle into the picturesque setting, an air of unease grows. Gretchen is tormented by eerie sounds and disturbing visions, which lead her to a horrifying discovery about her family’s dark secrets entwined with the resort’s facade of tranquility.