Amelia (Essie Davis), the heroine of Jennifer Kent's horror movie THE BABADOOK, is an Australian single mother haunted by memories of her late husband's tragic death. He was in the midst of taking his very pregnant wife to the delivery room when the couple had a devastating car wreck. Mother and baby were saved; dad perished. That was six years ago. Now, as the story opens, Amelia is raising her young son Samuel (Noah Wiseman), a sweet-natured but very precocious and troubled little boy. On a nightly basis, Samuel grows convinced that monsters lurk beneath his bed, and he has even constructed homemade weapons, such as a miniature wooden catapult and crossbow, to fend off the invading enemies. His eccentric behavior alienates his schoolteachers, who insist on removing him from a group setting in the classroom in favor of a special-needs situation with a one-on-one tutor. Meanwhile, Samuel's conduct stresses Amelia to the breaking point. The situation at home grows much more bizarre when Samuel asks his mom to read to him, and produces a strange children's storybook from his bedroom shelf. Entitled "The Babadook," it's an eerie pop-up book with charcoal illustrations of a demonic figure that announces itself by knocking at the door of a house six times ("Ba-ba-ba-DOOK-DOOK-DOOK"), and then devours all who reside within. Neither Amelia nor Samuel have ever seen this volume before, nor do they know how it turned up in their home. Stranger still, it lacks an author and publishing information. The book instantly has Samuel in tears, and Amelia plans to dispose of it, but that same night, six knocks sound on the door and rattle the house...