Undertone Review: A24’s $500,000 Horror Hit Is the Scariest Movie You’ll Ever Hear

Some horror films ask you to look. Undertone asks you to listen. Written and directed by Ian Tuason in his feature debut, this A24 chiller was shot for a reported $500,000 inside his parents’ house in Toronto. It premiered at the Fantasia Film Festival in July 2025, set off a bidding war among distributors, and made its US debut at Sundance in January 2026. A24 opened it in theaters on March 13, where it earned $9.3 million over its first weekend and the film has grossed over $19 million.

It has since become one of the year’s surprise horror successes. The film started streaming on HBO Max on June 26, 2026, and it’s also available to watch at home on digital platforms. Warm up the headphones, because here’s our review.

The Story: Ten Recordings and a House That Listens

Evy, played by Nina Kiri, hosts a podcast about all things creepy. She’s also moved back into her childhood home to care for her dying mother, who lies catatonic in bed for nearly the entire film, with Michèle Duquet in the role. Her only break comes when she records her show with her friend Justin, played by Adam DiMarco. He’s the believer, and she’s the skeptic.

Then her podcast is sent ten audio recordings of a young pregnant couple who’ve been hearing strange noises in their home. At first, Evy and Justin treat the clips as material for a new episode. They play them, rewind them, and try to figure out what’s making the sounds. But the further they go, the more the recordings seem to echo Evy’s life. She’s pregnant, her mother is dying upstairs, and her house is full of crosses, paintings of Jesus and Mary, and other religious objects. Each new clip scratches at her sanity, and Evy begins to realize that the story she’s listening to is a mirror of her own.

A Movie Built Out of Sound

What makes Undertone special is its commitment to a single idea. The film stays locked in Evy’s point of view for its entire 94-minute runtime. Almost every scene takes place inside her house, and you never get a break from her perspective. When she puts on her headphones, the soundtrack narrows into a muffled, closed-in hum, so you hear only what she hears: the podcast, the clips, and her own breathing. It’s a clever way to trap the audience in the same nightmare as the character.

The sound design is the star, and it’s remarkable. A creaking floor, a whispered voice, and a faint distorted noise in the background of a recording all become frightening. Tuason understands that what you imagine is often scarier than what you see, and the film gives your imagination plenty of space to work. Instead of relying on jump scares or a booming score, it uses silence, subtle audio details, and the sensation of not being sure whether you heard something at all.

The visuals work the same way. Cinematographer Graham Beasley keeps the camera slightly tilted, sometimes subtly and sometimes dramatically, and he often places Evy at the edge of the frame while the rest of the shot shows a dark hallway or the top of a staircase. Watching someone sit and record a podcast isn’t exactly cinematic, so the film encourages your eyes to wander. You catch yourself scanning shadows, wondering whether something is standing in a doorway. Most of the time, nothing is there. But your mind keeps looking, which is exactly the point.

Nina Kiri Carries Every Scene

This is a one-woman show, and Kiri is excellent. Evy is exhausted, grieving, and a little defensive, and Kiri lets those feelings show without overplaying them. She’s believable as a skeptic who is slowly forced to question what she hears, and she’s just as convincing when the fear starts to unravel her. Because the camera barely leaves her, her face and body language tell much of the story.

DiMarco has a lighter role, but he adds warmth and humor as Justin, whose enthusiasm for the paranormal provides a contrast to Evy’s doubt. The two have a natural chemistry that makes the podcast scenes feel believable, and the banter gives the film a human anchor before the horror takes over.

What the Film Is Really About

Underneath the scares, Undertone is a film about grief, faith, and impending change. Evy is watching her mother slip away, she’s facing a difficult decision about her own pregnancy, and she’s living surrounded by religious imagery she may or may not believe in. Life and death, good and evil, belief and doubt all move through the story.

Tuason doesn’t spell any of this out. The film trusts you to connect the dots, and it never offers a simple explanation. Some viewers may wish for clearer answers, particularly in the final act, which spirals into image and sound in a way that’s meant to unsettle rather than resolve. But that ambiguity is part of what makes the ending so effective. It lingers in your head long after the credits.

Where It Might Not Work for You

Undertone is a slow burn. The first half builds tension patiently, and viewers expecting constant action or a fast-moving plot may find it too quiet. The story is also very focused. Nearly everything happens in one house, with one main character, which gives the film intensity but limits its variety.

The ending won’t satisfy everyone, either. If you prefer horror that explains itself, this isn’t that. And the film really needs good headphones or a good sound system. Watching on a laptop speaker will take away much of what makes it special.

What Comes Next

The film’s success has opened big doors for Tuason. Blumhouse hired him to direct the next Paranormal Activity film, a series that also began with a micro-budget horror made inside a house, and he has said he has ideas for two more Undertone installments. After watching this, it’s easy to see why studios are excited.

The Verdict

Undertone is a terrifying, intelligent, and beautifully crafted horror film that proves how much you can do with a tiny budget and a great idea. Its sound design is among the best in recent horror, Nina Kiri gives a powerful performance, and its slow-building dread pays off in a final act you won’t forget. Put on your headphones, turn off the lights, and press play.

Rating: 4.5/5

Watch the Trailer

Quick Facts

• Title: Undertone
• Writer/Director: Ian Tuason
• Genre: Supernatural Horror
• Runtime: 1h 34m (94 minutes)
• Starring: Nina Kiri, Adam DiMarco, Michèle Duquet, Keana Lyn Bastidas, Jeff Yung
• Cinematographer: Graham Beasley
• Production: Slaterverse Pictures, Black Fawn Films
• Distributor: A24
• Premiere: Fantasia Film Festival, July 2025. US premiere: Sundance, January 2026
• Theatrical release: March 13, 2026
• Streaming: HBO Max, since June 26, 2026
• Box office: Over $19 million (reported budget: $500,000)

Where to Watch

Undertone is streaming on HBO Max, and it’s also available to rent or buy on digital platforms through A24.

Have you seen “Undertone”? Tell us how it sounded in the comments below.