“There’s nobody here except for us.”

Here’s how effective Babak Anvari’s Under the Shadow is: at one point during the film’s proceedings, a ghostly presence makes itself known by appearing under a hovering bedsheet. It’s the oldest, most hoary ghost cliche in the book — and it works completely. So fine-tuned is Anvari’s creepy, unsettling domestic horror show.

Set in Tehran during the final days of the Iran-Iraq War, Under the Shadow finds Shideh (Narges Rashidi) struggling to adapt to change. She was a promising med student before the war, but now her checkered past of activism has all but ensured she can never practice medicine. Her husband Iraj (Bobby Naderi), a doctor himself, is sympathetic, but also thinks it might be best if Shideh put her dreams on hold for a while, much to Shideh’s boiling resentment. The couple live in an apartment with their young daughter Dorsa (Avin Manshadi), and their lives consist of hurrying to the basement when air raid sirens sound.

Possible air raids aren’t the only thing the fear. When Iraj is called to the front lines, Shideh and Dorsa are left alone — or are they? It becomes apparent quickly that there’s another presence in the apartment, and as more and more residents flee for safer locations, Shideh and Dorsa become more and more isolated. And possibly trapped with a malevolent spirit.

There’s more than a passing resemblance here to Jennifer Kent’s 2014 The Babadook, as Shideh begins to crack under the obstinance of her troubled child. Is Dorsa merely acting out, or is she under the sway of something supernatural? Or is the trouble residing entirely in Shideh’s stress-fractured mind? Anvari’s script toys with the viewer, drawing us deeper into Shideh’s mindset. She values her independence, and it’s clear she’s furious over the way her country has changed. In one of the film’s most telling sequences, Shideh flees the apartment after a particularly terrifying confrontation with the possible spirit only to find herself arrested for not wearing a chador.

Anvari and cinematographer Kit Fraser layer the film with eerie imagery that never fails to unsettle: a dud bomb crashes through a roof and sits half-buried in the floor; a doll goes missing; an X taped across a window in case it shatters; the wind whips around a tarp covering the bombed-out roof. At the same time, there are moments here that border on being plodding. The film is only about 84 minutes, but feels much longer due to occasional issues of poor pacing.

Pacing issues aside, Under the Shadow is a potent thriller that’s bolstered by a fierce performance from Narges Rashidi. Rashidi is in nearly every single frame of this film, and she commands the screen as we watch her character crumble before our eyes. The crumbling is understandable — there’s a palpable weight pressing down on Under the Shadow; an uneasy feeling that no matter what the outcome of the story things will never be the same again. A large chunk of horror films don’t even consider trafficking in the type of heavy concepts that are peppered through Anvari’s script, and that’s what truly makes Under the Shadow remarkable.