Nyctophobia, or an extreme fear of the dark, is a common and universal phobia that afflicts the young and old alike. Horror often exploits that fear, using darkness to conceal all forms of evil lying in wait. The Power, the latest by writer/director Corinna Faith, uses the late 1973 rolling blackouts that plunged London into darkness every night, caused by a miners’ strike, as a backdrop for this hospital set haunter. Faith uses a familiar period ghost story as a foundation to create an emotionally powerful tale full of claustrophobic dread and nyctophobic-induced scares.

Young nurse Val (Rose Williams) gets off on the wrong foot with her supervisor on her first day on duty. As a result, she’s assigned the night shift to watch over the remaining patients in a ward of a crumbling hospital. With most of the staff and patients already relocated to a new facility, it leaves Val almost entirely alone in a strange building nearly enveloped by darkness thanks to the city’s rolling blackouts. Struggling with her paralyzing fear of the dark proves extra tricky when it seems a malevolent presence thrives in the shadows of the hospital’s corridors. Is its relentless pursuit of her an indication that there’s something seriously amiss with this place, or is it all in her fragile mind?

From the outset, Faith teases a deep trauma from Val’s past that triggered her aversion to the dark. Val’s history, unfurling slowly throughout the evening, plays a vital role in the events that transpire. The nurse’s impoverished background means she’s instantly looked down upon by most around her at the hospital, especially from a fellow nurse and former schoolmate Babs (Emma Rigby). It’s also what connects her to young runaway patient Saba (Shakira Rahman), with whom she sees a kindred spirit. Val and Saba’s bond provides the emotional backbone, as the two forge a connection based on being disbelieved by everyone around them. That connection grows deeper as the entity lurking in the dark grows more prevalent and angry, threatening harm to all. The more hysterical that Val becomes, the more she’s written off as mentally unfit for the job.

Faith builds a chilling atmosphere, first by emotionally isolating her protagonist then by letting her get lost in the winding halls of a near-abandoned hospital. The blackout enhances the setting’s disorienting nature, with the nervous nurse growing more frantic as she rushes to find the next sliver of light cast by a selectively placed generator. Those large stretches between the generator’s red glow or candlelit wards create a vacuum for encroaching terror—the more the hours tick by, the less reprieve Val receives. The filmmaker demonstrates a thrilling ability to mount dread and suspense while ratcheting up Val’s psychological stakes. Faith escalates Val’s story at a brisk and steady clip.

Much of the film rests on Williams’ shoulders. She plays Val as the meek but eager to please type, completely undone by fear. The gradual transformative arc from timid to unhinged to asserting her inner strength retains rooting interest throughout, even when some of the scare pieces retread familiar ground. It’s Val- and Saba, to a smaller extent- that sets this film apart from other period set haunted house stories.

As the narrative barrels toward its conclusion, it becomes clear that there’s a brilliant duality to the film’s title. Faith’s latest innovatively draws from historical blackouts on the surface level, forcing her heroine to confront dark secrets and trauma during a power outage. But there’s a subtext that gets drawn to the forefront, with Val finding power from her pain that she didn’t know she possessed. It imbues a familiar haunter with a profound and triumphant catharsis. Faith wraps a timeless tale in period clothing, delivering an unsettling atmosphere and compelling characters. While it does employ some standard tropes, The Power succeeds in crafting an emotional powerhouse with a few memorable scares.

The Power releases on Shudder on April 8, 2021.