A brother and sister reunite 11 years after their parents’ violent deaths: he wants simply to reconnect with her, while she wants to destroy the cursed supernatural mirror she hold responsible for their murder.

Writer/director Mike Flanagan originally shot Oculus as a short film in 2006, intending to demonstrate his ability to direct a horror film. It did not become a feature until 2013, where it formed the basis of his second full-length work. Today he is a widely respected and popular maker of screen horror thanks to the likes of Gerald’s Game, Doctor Sleep, and the Netflix serials The Haunting of Hill House, Midnight Mass, and The Fall of the House of Usher. While Oculus is far from perfect, it is possible to see the skilled filmmaker’s promise even when he was just getting started.

The first act of Oculus is, it must be said, something of a drag. It introduces siblings Tim (Brenton Thwaites) and Kaylie (Karen Gillan), as well as their violent past. Tim has recently been released from psychiatric care, where he spent more than a decade after allegedly murdering their parents. Kaylie does not believe that he did, and instead has been tirelessly working with their estate to spend a night in their childhood home with their father’s curious antique mirror. Through repeated flashbacks we are introduced not only to the younger Tim and Kaylie (Garrett Ryan and Annalise Basso) but also their ill-fated parents (played by Rory Cochrane and Katee Sackhoff).

Tim does not believe in Kaylie’s story of supernatural possession and demonic hallucinations, but is persuaded to witness her attempt to prove it. In the lead-up to her experiment, recording the mirror with a variety of video cameras and sensor devices, Oculus is a quite tedious experience of slightly disorienting flashbacks, genre stereotypes, and wasted time. The set-up is clear, the characters are not particularly complex, and there is an awful lot of screen time spent waiting for the action to finally get to the house and the mirror.

Once the experiment begins, Oculus becomes a strikingly different film. The jumps from present-day action to flashback become more inventive and interesting. An entire monologue’s worth of back story enlivens the story – and should clearly have been positioned right at the very beginning of the film. Flanagan’s screenplay begins to play around with ideas that are not only smart storytelling but hugely effective horror.

The cast are uniformly strong, and the film creatively framed. It builds tension incredibly well, and adds in tradition jump scares, and flinch-inducing moments of bodily violence.

Most of all, it is a master class in affecting dread, arguably the most difficult horror element to deliver on-screen. Flanagan introduces a horrifying premise into the film, and it is one that the audience is easily able to unravel and understand well before the affected characters do. The film’s greatest strength is its inevitability. Perhaps its conclusion is a little too on the nose, and lacks the insidiousness that boosts the middle section. Perhaps it takes a little too long to kick into gear and deliver its best scares. On the other hand, this is a strong early career movie that promises an outstanding directorial career to come – a career that has already paid off strong dividends in Flanagan’s subsequent work.