At its best, horror is a genre that attempts to explore the human emotion of fear, an emotion that is more complex than it is generally given credit for. This complexity gives it the potential for a wide variety of expression on film. It could be psychological or visceral, supernatural or based in reality. In his new film Oculus, writer/director/editor Mike Flanagan reveals a sincere interest in exploring fear through a variety of these facets.

The film tells its story through the shuffling back and forth of two time periods in the lives of siblings Kaylie (played as a child by Annalise Basso and as an adult by Dr. Who’s Karen Gillan) and her little brother Tim (played as a child by Garrett Ryan and as an adult by Brenton Thwaites). In present day, Tim reconnects with his older sister following his release from 11 years of psychiatric care. Unfortunately, Kaylie wastes no time in returning both of them to the horror that put him there in the first place.

At the center of that horror is an elaborate antique mirror that Kaylie is convinced is responsible for a terrible tragedy that befell their parents (Rory Cochrane and Battlestar Galactica’s Katee Sackhoff) when Kaylie and Tim were children. Kaylie has managed to get a hold of the cursed mirror, and she enlists the help of the freshly released Tim in her elaborate scheme to simultaneously destroy the object while getting solid evidence of its power, which she hopes will clear the name of her family. The film starts with occasional flashbacks to the earlier time period, but as it progresses the streaming between past and present gets more frequent until both timelines seem to merge into one.

Lots about the story could have fallen apart, but they worked enough to keep the narrative in place. At its best, the nonlinear story structure can be a jarring mess, but Flanagan makes it serve the story and heighten the feeling of the evil mirror’s reality-bending powers. Because he had the unique opportunity to write the script knowing he would direct and edit the film, he had the ability to keep the action hallucinogenic without it devolving into incoherence. The inanimate antagonist is also something that can seem silly, but it works. There is a long tradition of haunted objects in storytelling across multiple cultures, and it’s nice to see it have a place in film. What sells this kind of abstract horror is a false reality.

That sense of false reality is where the real strength of Oculus should lie, but it is carried by the strength of the acting from both the adult and child versions of Tim and Kaylie. Since the scares rely more on dread than overt gore or a high body count, Gillan, Thwaites, Ryan, and Basso had to deliver the kind of performances that make the audience care for their well-being. The use of children as central protagonists here isn’t a cheap way to elicit audience sympathy, but rather an intentional part of the storytelling. Katie Gillan really does shine in her role, and at one point even makes a potentially boring expositional infodump seem more like a series of devilish campfire horror stories. Katee Sackhoff as the mother also gives a solid performance as a character type she isn’t necessarily known for.

Oculus probably could have been made more interesting by committing more fully to the hyper-reality of the horror in question. Most of the mind bending relies on the progressively more discordant story structure and a few questions about whether or not what the characters see is real. But the majority of the time, familiar haunted house tropes like flicking lights or strange noises are used, which can feel a bit tired. One wonders what could have been if more imaginative scenarios were employed to show the consequences of an object so otherworldly.

Despite this, Oculus is the kind of horror film that will probably be remembered. There are clear reasons for telling this story that go beyond just another roller coaster-type thriller. It explores how central childhood is to the feelings of terror and dread in human beings, how much people rely on their perceptions of what is going on around them, and probably most harshly (without giving too much away), how even when there is true evil in the world, sometimes our greatest downfall can be ourselves. It can be scary stuff!

Oculus opens in theaters nationwide on April 11.