When a new family moves in next door, their young daughter, Megan, quickly captivates Laura (Andrea Riseborough), stirring up painful memories of her own daughter who died several years previously. Before long, Laura's memories turn to obsession as Megan's unsettling behaviour begins to convince her of something supernatural. As Laura's determination to get to the bottom of it becomes all consuming, her family begins to fracture and the line between the extraordinary and the real becomes ever more obscured in this haunting story about a mother's love.