When the hedonistic and glamorous couple of Peter and Cara move into the Lyntons, a dilapidated English country mansion, Frances Jellico, the woman living in the upper floors researching the architecture in the mansion's gardens. One day Frances accidentally finds a peephole beneath a floorboard in her bathroom, giving her access into the private lives of her new neighbors. Then, surprisingly, Cara and Peter welcome her into their lives as a friend, but as Frances gets to know the couple it becomes clear that something is off between them, and things spiral out of control leading to a terrible crime that will sear their lives forever.
