Set in late 1870s rural England, 15-year-old Lara lives with her father and her strict governess, Miss Fontaine, in total isolation, and is struggling to find an outlet for her curiosity and burgeoning sexuality. When a carriage crash nearby brings a young woman, named Carmilla, into the family home to recuperate, Lara is enchanted by Carmilla. The pair strike up a passionate same-sex relationship, which strikes fear in the heart of Miss Fontaine, who begins to fear (rightfully) that Carmilla is a vampire, and a complex triangle emerges between the three women.