A widowed Amelia Vanek (Essie Davis) notices her son Sam (Noah Wiseman) exhibiting disturbing behaviour. Things get even worse after Sam asks his mother to read a book called Mister Babadook. The tale describes a monster that tortures anyone who's aware of its existence. Amelia becomes increasingly suspicious of the novel when Sam insists that the Babadook creature is real. And those suspicions quickly become reality.