Bare, labyrinthine office corridors, endless beige-yellow walls, the incessant, unbearably loud hum of fluorescent lights: “Backrooms” depicts a new kind of nightmare—a deserted parallel world of repetitive, windowless floors that, at first glance, mirrors our reality yet slips further from it with every step. One of the most innovative horror films of the year, based on an internet phenomenon and directed by Kane Parsons, who is just 20 years old.