Director Kane Parsons was only 16 years old when he first introduced the concept of Backrooms to the world via a YouTube series. Fast forward a few years, and he has quickly commanded the attention of A24, becoming the youngest director of any of their features, just 19 years old when the film started production. And the result proves A24 right; he has a keen eye for compelling storytelling and unnerving imagery, marking him as a young horror filmmaker with serious promise.

Chiwetel Ejiofor plays Clarke, a man who, suffice it to say, isn’t exactly doing well. His world takes a mind-bending, terrifying turn one fateful night when he discovers a hidden world beneath his store. Not one filled with magical creatures and beautiful forests, but a massive maze of never-ending office buildings.

After what seems like a long time spent setting up the story, the film jumps into its central nightmare. From the moment we enter the backrooms, it’s constant dread. Tension builds from every corner we turn, and once we are in there, it never lets up. The effective score by Kane Parsons and Edo Van Breemen plays a massive part in the unease, further immersing us in a state of never-ending fear. Every time we see a new area of the backrooms, it feels like there is something waiting right around the bend, just out of view. Unnerving stuff.

Ejiofor, as always, delivers a phenomenal performance, whether he is painfully conveying the issues in Clarke’s marriage or frantically trying to describe the unbelievable world he has discovered. Renate Reinsve also delivers a chilling performance as another person with her own past demons, also caught up in this nightmare. With only a couple of other actors in the film, most of it falls on the shoulders of the two leads, and they deliver in spades. Mark Duplass, who has made a name for himself playing offbeat, quirky characters (for reference, see Creep or Safety Not Guaranteed), also proves to be a standout.

With seemingly minimal CGI work, Backrooms appears to be doing a lot with practical effects, and it is very convincing. From the built sets to the designs of other elements in this nightmarish complex, the creative team deserves applause for the visually striking and downright unsettling creations. The jump scares are extremely well done and, unlike most horror movies of late, they do not simply set you up with fading music and a sharp burst of strings to trick you into a startled jump. These ones catch you off guard.

The screenplay by Will Soodik keeps its focus on preserving the mystery, leaving things vague when it comes to the exploration of the concept. Those who approach the film looking to be scared and entertained will enjoy it immensely, but those after more in the explanation department may come away slightly frustrated with the end result.

Backrooms is a very well-executed horror film that sends chills down your spine and leaves its mysteries crawling around in your head.