Undertone, one of the most anticipated horror films of 2026, made its U.S. premiere at the Sundance Film Festival in a packed midnight screening where it very much lived up to its hype.
It’s one of the most genuinely scary films we’ve seen: If there’s an award for keeping audiences up at night, Undertone should easily win it.
The Canadian horror film, picked up by A24 after its world premiere last summer at the beloved Montreal genre festival Fantasia, follows a young woman named Evangeline, or Evy (an outstanding Nina Kiri), who is caring for her dying mother (a mostly silent, but very effective, Michèle Duque). She also co-hosts a podcast focused on supernatural phenomena.
A24 cleverly built on the early buzz for the film by releasing an eerie online video consisting of some upsetting sounds. Internet sleuths, including us, quickly realized that its weird glitchy audio was a backwards recording of the children’s song “Baa Baa Black Sheep.” (See video, above.)
Creepy recordings are very much a plot point of Undertone. Evy co-hosts her podcast with Justin (Adam DiMarco, also great), who tells her that someone has anonymously sent him a series of creepy audio files. They turn out to be of a couple who have some sleep issues.
Evy and Justin record the podcast remotely, rather than in the same room. In fact, Evy does almost everything remotely. Though she seems to be in a relationship, she spends almost all her time roaming her mother’s old house, which is decorated mostly with religious iconography.
As the anonymous audio files get more and more alarming, the house’s dark corners and emptiness become more and more disquieting.
The Making of Undertone
The home in the film is the real-life Toronto family home of writer-director Ian Tuason, who was inspired to make Undertone while caring for his own sick parents, both of whom have died. In a post-screenng Q&A early this morning, producer Dan Slater explained that Tuason was unable to attend due to a bad allergic reaction to peanuts. He said Tuason would be OK.
The filmmaker’s absence only added to the dark, effective mystery of the film. Slater and fellow producer Cody Callahan explained that Tuason wrote every single sound into the film — from the backwards recordings that emerge in the anonymously sent audio files to the many alarming scratches, glitches and thumps that prove, again and again, even more jarring than visual jump scares.
Tuason also packed the film with audio mysteries for audiences to unravel.
“Everything was very intentional,” Slater told the Sundance audience. “This is a movie that, if you re-watch, you’re gonna see more of that. You watch it backwards, you’ll see a lot more.”
That’s right: The fun game of reversing the audio in the A24 promo video will also be helpful in future viewings of the film.
Kiri is in almost every scene of The Unheard, and commits completely. She said Tuason’s personal stake in the story inspired everyone.
“Because this was his home and such a personal story to him, and the energy doing this movie was so supportive, there was something there that made us all work harder and do a good job… because of his generosity to let us into his home and make this,” she said in the Q&A.
Kiri often heard the creepy audio files in the film for the first time during filming, at the same time her character did.
“I think I learned that there are situations where I can be open to the energy, even if the energy scares me,” she said. “And then there’s situations where I’m like, ‘No — this is where I’m going to close myself off.'”
How We Recommend Watching Undertone
This is how I saw Undertone, and how I recommend you see it, too, if at all possible: I waited outside in the mountain cold, with hundreds of others attending the final Park City edition of Sundance before it moves next year to Boulder. But any cold night will do.
I was barely awake at the start of the movie, since it was midnight and it had been a very busy day. The people next to me occasionally shifted, and I was so tired that I jumped whenever they did.
Soon I got completely rapt in the mesmerizing, sad darkness of the film. What makes it most effective are the casually cruel moments, and the sense of powerless Evy begins to suffer as she tries to parse horror from, and to, audio files. We quickly realize how unprepared she is for what she’s taken on.
As we filed out into the cold night at 2 a.m., to icy sidewalks and eventually our beds, a Sundance volunteer smiled ironically: “Sleep well.”
I’m sure no one did.
The Undertone arrives in theaters March 13 from A24.
Main image: Nina Kiri in Undertone. A24.
