When Sylvia looks out her bedroom window at night and sees a child face down in the pond next door, she races into her neighbour's garden. But the pond is empty, and no-one is answering the door.
Wondering if night feeds and sleep deprivation are getting to her, she hurriedly retreats. Besides, the fact that a local child has gone missing must be preying on her mind. Then, a week later, she hears the sound of a man crying through her bedroom wall.
The man living next door, Sam, has recently moved in. His wife and children are away for the summer and he joins them at weekends. Sylvia finds him friendly and helpful, yet she becomes increasingly uneasy about him.
Then Sylvia's little daughter wakes one night, screaming that there's a man in her room. This is followed by a series of bizarre disturbances in the house.
Sylvia's husband insists it's all in her mind, but she is certain it's not - there's something very wrong on the other side of the wall.