Amelia (Essie Davis), the heroine of Jennifer Kent's horror movie The Babadook, is an Australian single mother haunted by memories of her husband's tragic death. He was in the process 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. Samuel is convinced that monsters lurk beneath his bed, and he has even constructed homemade weapons (such as a crossbow and a miniature wooden catapult) to fend off the invading enemies. His eccentric behavior alienates his schoolteachers, who insist on removing him from a group setting in the classroom and setting him up with a one-on-one tutor. Meanwhile, Samuel's conduct is stressing Amelia to the breaking point. The situation at home grows much more bizarre when Samuel asks his mom to read to him, and removes 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 on the door of a house six times ("Ba-ba-ba-DOOK-DOOK-DOOK") and then devouring all who reside within. Neither Amelia nor Samuel has 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... This is essentially a good, scary, old-fashioned shocker -- a throwback horror picture that grips us with pounding in the night, startling effects such as the appearance of roaches and pools of black blood, and lightning-flash manifestations of the supernatural. Kent employs a particularly wise strategy in terms of introducing the Babadook. She first defines its shape and form via the charcoal pictures in the kids' book, where it looks like a terrifying apparition that seems pulled from our darkest and most buried fears: With its black top hat, coat, and extended razor-like claws, the Babadook looks like the love child of Jack the Ripper and Nosferatu. For much of the first hour, Kent keeps the demon off camera -- which allows the dread to build inside us -- until we finally begin to see its shape subtly manifest in the background of scenes. It's a truly chilling effect that plays on our subconscious terrors, and the way that the threats build is also horrifying. To Kent's credit, the Babadook has a clear-cut motivation for terrorizing mother and son that gradually becomes apparent, and that aim feels credible enough to make one's blood run cold. The occasional doses of black humor -- much of it derived from weird supporting characters, such as a ghoulish cop and a snide pair of social workers -- also feel refreshing and provide comedic relief from the tension. Only the conclusion of the movie seems off-base. Once the story sets up the threat of the Babadook, unveils its intentions, and pits mother and son against it, the narrative slams into a brick wall. You find yourself wondering how in the world the tale could possibly arrive at a credible resolution (let alone a happy one), and it ultimately doesn't wrap things up -- not really. While Kent scores points by avoiding cataclysmic violence at the end (there are no bloodbaths here), the so-called solution that she does concoct is risible: It throws all logic and sanity out the window. This could have been a minor horror classic, but it falls short of the mark because Kent & co. never tie up the loose ends satisfactorily. Still, for much of the way, The Babadook is a commendably restrained frightfest that works the audience into a state of almost unbearable intensity. Story flaws aside, it announces a director of great skill, intuition, and imagination in Kent, and features sublime performances by Davis and Wiseman that help sell the more extreme twists.