A24’s latest horror film uses sound, isolation and grief to create a deeply unsettling experience

As horror continues to dominate the 2020s, A24 is preparing to release what critics are calling one of its most unsettling projects yet. Ian Tuason’s “Undertone,” which premiered at the Sundance Film Festival, has emerged as a striking psychological horror that relies less on shocks and spectacle and more on atmosphere, sound and dread that seeps under the skin.

Rather than leaning on jump scares or heavy-handed music cues, Tuason builds fear through restraint. The film uses negative space, tilted framing and a relentlessly immersive soundscape to place the audience inside the same nightmare as its central character. It does not guide viewers gently through its themes or offer neat explanations. Instead, it demands to be felt rather than understood.

“Undertone” unfolds almost entirely through the perspective of Evy, played by Nina Kiri, a podcaster who returns to her childhood home to care for her dying mother. Her mother lies catatonic in bed for most of the film, a silent presence that hangs heavily over every moment. Evy’s life shrinks to the walls of the house, her responsibilities and the emotional weight of impending loss.

Evy finds brief escape through her paranormal podcast, which she co-hosts remotely with her friend Justin, played by Adam DiMarco. The podcast explores supernatural recordings sent in by listeners, with Justin eager to believe and Evy playing the sceptic. Their final planned episode centres on ten disturbing audio clips linked to a married couple who claimed they began hearing something unnatural inside their home.

As Evy listens and analyses the recordings, the boundary between investigation and invasion begins to collapse. The sounds from the tapes bleed into her surroundings, and the sense that something unseen is watching or listening becomes inescapable. Tuason keeps the camera close to Evy at all times, refusing to cut away or offer relief, heightening the claustrophobic intensity.

The house itself becomes an extension of the horror. Religious objects line the walls, symbols of faith sitting uneasily alongside the decay of Evy’s family life. Evy is also pregnant, and subtle scenes suggest she is questioning whether to continue the pregnancy. These personal struggles mirror the disturbing undertones in the recordings, which include infant noises and implications of violence, drawing unsettling parallels between creation, destruction and belief.

Tuason weaves these themes without explanation or emphasis. Grief, faith, life and death move in and out of focus, never settling into a clear message. This ambiguity is intentional. The film does not attempt to resolve its ideas or reassure its audience. Like a nightmare, it simply unfolds and leaves its marks.

Visually, the film amplifies unease through careful composition. Evy is often placed at the edge of the frame while dark hallways, staircases and doorways dominate the centre. The audience is encouraged to scan the background, to search for movement or shapes that may not be there. Over time, viewers begin to doubt their own perception, mirroring Evy’s unravelling grip on reality.

The slow-burning tension builds steadily toward a final act that critics have described as deeply chilling. As sound and image spiral into chaos, the audience experiences the same sense of entrapment as the protagonist. The film offers no clear answers about what the recordings truly contain or how much of Evy’s experience is psychological or supernatural.

In an era where many horror films over-explain their mysteries, “Undertone” stands apart by refusing to connect every dot. Its power lies in suggestion, in what is heard but not seen, and in what is felt but never fully understood.

Following its strong reception at Sundance, A24 acquired the film in a seven-figure deal. Tuason has since been selected to direct a reboot of the “Paranormal Activity” franchise, a sign that the industry sees “Undertone” not just as a successful horror film, but as the arrival of a significant new voice in the genre.

“Undertone” is set to open in cinemas on March 13.