A young American named Greta (Lauren Cohan) takes a job as a nanny for an 8-year-old boy in a remote English village. To her surprise, Greta learns that the child of her new employers is a life-size doll. They care for the doll as if it was human, which helps the couple to cope with the death of their own son 20 years earlier. When Greta violates a list of strict rules, a series of disturbing and inexplicable events bring her worst fears to life, leading her to believe that the doll is alive.