SUNDANCE: ‘Undertone’ Probes New Depths of Fear

Film is primarily understood as a visual medium, yet the auditory dimension is often overlooked. Undertone, the latest horror flick from A24, not only understands the importance of sound design but absolutely weaponizes it to maximum effect.

Written and directed by Ian Tuason in his feature debut, Undertone has a relentless, effective aesthetic that, combined with a dense lore, surgical deployment of its scares, a star-making turn from Nina Kiri, and a third act that will leave the audience with stress tears from the sensory overload, makes it a must-watch. Simply put, Undertone is the next big thing in horror.

Evy (Nina Kiri) is a true crime podcaster. With her co-host Justin (Adam DiMarco), she explores various paranormal phenomena. Privately, she is in a dark place. As Nina takes care of her ailing mother in hospice care (Michèle Duquet), she deals with an absentee boyfriend as she begins to suspect her own pregnancy.

On the day of their next podcast recording, Justin introduces some audio clips he was sent anonymously. The haunting clips send Evy down a spiral as she begins to suspect that the metaphysical events in the audio recordings are bleeding into her personal life. 

Nina Kiri delivers a captivating and star-making performance in the latest from A24.

Stuck essentially doing a one-woman show, Nina Kiri is supersonic. Although this is perhaps an overused term, Kiri’s Evy feels less like a movie character and more like a real flesh-and-blood human. She has real interiority; her isolation is palpable, and the deep anxiety of having to take care of a dying parent who could pass away courses through her performance.

Her trip down the rabbit holes feels like her trying to escape her current predicament while also making sense of it. Kiri’s co-star DiMarco believably recreates the cadence of a podcaster in his off-screen role, while Duquet makes a meal out of a role that mostly requires her to lie down in a catatonic state. 

Ian Tuason makes a show-stopping debut. His visual style, aided by cinematographer Graham Beasley, prioritizes leaving negative space in the frame, so that whenever Evy is listening to the audio files, the audience is constantly on edge, looking for something to pop out.

It helps tremendously that the sound design surges past simply scary to be absolute nightmare fuel. Tuason doesn’t front-load the film; the audio recordings start subtly, and as the story unspools, more disconcerting noises creep in. At a certain point, the line between what’s part of the recordings and what Evy is hearing in her home blurs. 

Undertone cements itself as the next big thing in horror, 

What’s impressive about Undertone is that the audio recordings and Evy’s story both serve as parallel narratives that are equally satisfying in and of themselves. There’s a deep loneliness within Evy’s narrative that directly mirrors the director’s own experience taking care of his sick parents in their final moments. In fact, the film is even shot in his home, adding a layer of authenticity to the pain throughout.

The actual lore on display in the audio recording feels straight-up nefarious. Playing on Catholic guilt to build a dense lore that’s as satisfying to think about after the film as it is to experience in it, Undertone borrows from real Biblical characters. 

What takes Undertone from an effective slow-burn to a modern masterpiece is its third act. A series of early film plants begins to be paid off, piece by piece. Evy’s character arc reaches a sickening conclusion as the truth of the audio files fully seeps into her world. The deliberate framing Ian Tuason has employed crescendos as the audio design hits an overwhelming zenith.

There are horror moments that destroy the artifice of this being a narrative feature, just how hard they reach out to the audience. Without exaggeration, the final moment of this film is one that I believe will live in horror cinema history forever, a face-melter of a finale that justifies the entire project.

Undertone is a film that feels like it actively curses the audience. Coming from a genuine place, Ian Tuason draws on the auditory dimension of horror in ways that have never been done before. Supplemented by an intriguing lore and knockout work from Nina Kiri, it’s easy to claim the latest horror flick as the next big thing. Truly, Undertone is a can’t-miss horror event that will be mirrored for years to come by up-and-coming filmmakers. The message is clear to those who will listen: Undertone is the real deal.

Undertone screened as a part of the 2026 Sundance Film Festival and premieres in theaters on March 13, 2026.