Lydia (Maisie Williams) and Abbie (Pugh) are best friends who attend an all-girls school in this 2014 film. One day, Abbie begins to have fainting episodes, and she unfortunately dies. Soon after, the rest of the students begin to experience similar fainting spells, including Lydia. While the movie largely focuses on this mysterious outbreak, it also deals with Lydia's sexuality, her home life, and her relationship with her mother.