For years, the Sundance film festival has served as a launchpad for films that end up garlanded with awards: Oscar winners first screened at the event include Precious and Boyhood. But as genre fans are well aware, it’s also long been a haven for the best horror films the industry has to offer.

Recent spooky sensations to have premiered at Sundance include The Babadook, Jennifer Kent’s powerhouse debut, which defied genre conventions to win a slew of awards and land on countless top 10 lists in 2014; and Robert Eggers’ eerie period thriller The Witch, which is bound to do solid business when it opens in late February, just over a year after winning the festival’s best director award. (The Guardian’s Jordan Hoffmann praised The Witch in his four-star Sundance review, writing that “its focus on themes over plot is what elevates it to something near greatness.”)

This year’s unarguable horror standout was Under the Shadow, the feature-length debut of Iranian director Babak Anvari. The low-budget Farsi-language film arrived in Park City with a Netflix streaming deal already in place; it will also be screened in cinemas. Set in Tehran in 1988, at the height of the Iran-Iraq war, when Iraqi bombs pelted down, Under the Shadow centers on mother Shideh (Narges Rashdi in a star-making performance), who is forced to care for her young daughter Dorsa (Avin Manshadi), after Shideh’s husband is ordered off to battle.

Under the Shadow: demons come out to play. Photograph: PR/Sundance Film Festival

The film doesn’t announce itself as a horror until some distance in, when Dorsa begins alluding to a demonic presence that haunts her. Up until that point, Under the Shadow spends its time building up Shideh as a fully formed character at odds with her surroundings, so that when the terror hits, it means something.

Anvari’s debut is bracingly feminist in tone, with Shideh leading the charge as an aspiring doctor determined to resume her medical studies, but unable to in Iran due to her past political activism. Her husband, himself a doctor, can’t bring himself to understand his wife’s longing to forge a career for herself, saying during a heated argument that she’s trying to fulfill her mother’s dream – not her own. “Dead people can’t dream,” she solemnly retorts.

The film’s triumph lies in its ability to critique Iran’s post-revolution regime for its blatant sexism (in one harrowing sequence, Shideh is arrested for simply going outdoors without her chador), while still working as a full-throttle horror when the demons come out to play. Anvari proves himself to be a master at modulating fear: the jump scares are executed with effective precision, leading up to a magnificently intense climax.

Under its scares, Under the Shadow serves as an impassioned allegory for female oppression – but Anvari doesn’t shortchange horror fans. He delivers an entertainment that’s fun to watch, and subversively incisive for those willing to read between the lines.