Sisters explores the dark side of sibling devotion, striking a balance between character study and psychological horror. After a serious case of school bullying becomes too much to bear, sisters July and September move across the country with their mother to a long-abandoned family home. In their new and unsettling surroundings, July finds that the deep bond she has always had with September - a closeness that not even their mother is allowed to penetrate - is starting to change in ways she cannot entirely understand. Inside the house the tension among the three women builds, while outside the sisters meet a boy who tests the limits of their shared experiences.