A young American woman (Lauren Cohan) takes a job as a nanny in a remote English village, only to discover that the family's eight-year-old son is a life-sized doll that the parents care for just like a real boy, apparently as a way to cope with the death of their actual son 20 years prior.

When she doesn't follow a list of strict rules of what to do with the doll each day, including playing music and reading poetry to him, as well as fixing him meals when the parents go off on a vacation, a series of disturbing and inexplicable events lead her to believe that the doll is actually alive.