undertone

undertone follows Evy Babic, a recovering alcoholic who has temporarily returned to her suburban childhood home to serve as the sole caregiver for her estranged, catatonic mother. Evy's only tether to the outside world and personal creative outlet is co-hosting The Undertone Podcast alongside her longtime friend Justin. While Justin acts as the credulous supernatural enthusiast from London, Evy positions herself as the firm, grounded skeptic who seeks rational explanations for urban legends, cursed media, and paranormal phenomena.

Because of their time zone difference, the pair record remotely at 3:00 AM. Their routine takes a chilling turn when Justin receives an anonymous email containing cryptic acrostics and ten audio files sequentially labeled. The tapes document an expecting couple, Jessa and Mike, who originally set up overnight audio equipment to capture Jessa’s sleep-talking, only to inadvertently record a sinister descent into apparent demonic affliction.

As Evy and Justin dissect the recordings across multiple sessions—employing audio editing, noise filtering, and backmasking—the sinister contents of the files begin to bleed into the physical reality of Evy's home. Trapped inside a claustrophobic house filled with Catholic iconography, exhausted by the relentless demands of palliative care, and haunted by unresolved maternal resentment, Evy's skeptical foundation collapses as acoustic anomalies begin manifesting in the room around her.

Director Ian Tuason conceived undertone out of his real-life experiences serving as a caregiver for his ailing parents between 2021 and 2023. The core thesis explores how guilt, profound grief, and unresolved filial obligations weaken the psychic armor of the human mind, leaving an individual vulnerable to external and internal terrors.

Tuason uses the horror genre to argue that auditory imagination is far more terrifying than visual spectacle—what the human psyche constructs in the darkness of negative space and acoustic ambiguity is uniquely primal. Furthermore, the film critiques the detached voyeurism of true-crime and supernatural entertainment culture, demonstrating what happens when morbid curiosity invites genuine darkness into one's private sanctuary.

The film invites multiple complementary readings:

undertone emerged during the mid-2020s wave of "podcaster horror" and minimalist sensory cinema. Premiering in the Midnight section at Fantasia 2025 and Sundance 2026, the film quickly became a breakout title for A24.

Critics celebrated it as an evolution of the "found footage" genre into "found audio," demonstrating how intimate single-location filmmaking can generate immense cinematic tension without expansive budgets.

Audiences and critics widely praised the film's Dolby Atmos sound mix, Foley design, and innovative acoustic dread, alongside Nina Kiri’s commanding and emotionally vulnerable solo on-screen performance. The effective use of negative space, minimalism, and claustrophobic framing were also highlighted as standout achievements.

Points of criticism focused on the repetitive narrative loop alternating between audio sessions and caregiving tasks, as well as the ambiguous lack of conventional exposition or definitive plot resolution. Overall, it was regarded as a masterclass in acoustic tension and single-location horror.