There’s a certain breed of horror film that knows exactly which ingredients to pull from the pantry. A cursed object. A group of mismatched teens. A ticking clock. A teacher who conveniently has expertise in the one obscure subject that matters. Whistle checks every one of those boxes with the confidence of a film that’s studied the playbook, and for the first half, director Corin Hardy (The Nun) makes a strong case that familiarity doesn’t have to be a dealbreaker. It’s the second half where things go sideways.

The setup works well enough: after a family tragedy, Chrysanthemum “Chrys” Willet (Dafne Keen, Logan) transfers to a new school and inherits the locker of a student who died under horrific circumstances. Inside it sits an ancient Aztec Death Whistle, a skull-shaped relic that, once blown, summons the exact manner of each listener’s future death and drags it into the present. Her classmates blow it too, because of course they do, and suddenly a grey, post-industrial Canadian town masquerading as upstate NY becomes a hunting ground. It’s Final Destination meets The Ring, and if you’ve seen either of those, you already know the rhythm. The question is whether the execution earns its own lane.

For a while, it does. Hardy delivers a moody, desaturated atmosphere that feels like the town itself is running out of oxygen. Cinematographer Björn Charpentier gives the film a visual identity that a lot of mid-budget horror never bothers to develop. There’s a split-diopter shot early on, the whistle in sharp focus while a future victim blurs behind it, that’s genuinely striking. He also finds smart angles in a hospice scene involving mirrors that show real craftsmanship. The score from Doomphonic weaves between dark ambient textures and an almost retro synth pulse, interlocking nicely with the vinyl records Chrys plays in her room. For once, the music a teen character listens to actually feels like something a real person would choose.

Keen is terrific here, by the way, and it’s borderline frustrating that the material can’t keep pace with her. She plays Chrys as guarded and raw without turning grief into a single note, and she carries the film’s emotional weight so effectively that you wish the script trusted her more. The romantic subplot between Chrys and Ellie (Sophie Nélisse, The Book Thief) is one of the film’s genuine strengths. It’s refreshing to see a teen horror movie commit to a queer love story without hedging, and because of that, you actually root for these two to survive rather than just waiting for the next creative kill. Their chemistry gives the film real stakes, even when everything else around them starts to wobble. Nélisse is a touch bland on her own, but paired with Keen, they find something sweet and believable.

The supporting cast fills familiar slots. Sky Yang (Anniversary) turns in a committed performance as Rel, Chrys’s cousin, bringing both comic relief and genuine loyalty. The script never quite clarifies the circumstances of how Chrys came to live with Rel’s family, which is emblematic of a larger problem: Owen Egerton‘s screenplay spends a lot of energy fleshing out things that don’t matter much and skips over details that do.

Ali Skovbye and Jhaleil Swaby round out the core group as Grace and Dean, and Nick Frost (Get Away) shows up as Mr. Craven, the grumpy history teacher whose classroom is suspiciously wallpapered with Incan and Mayan posters just so you know he’s the expert. But the best performance outside of Keen belongs to Michelle Fairley (Small Things Like These), who appears in only two scenes as a dying woman with critical information about the whistle. Fairley understands the assignment completely and I could’ve watched an entire film built around her and Keen.

Now, about that whistle. The film is built on Aztec mythology, but the characters keep referencing Mayan customs and Guatemalan rituals as if these are interchangeable cultures. They are not. The cast itself is admirably diverse, a rainbow coalition of teens from different backgrounds, which makes it even more noticeable that the film has almost zero interest in engaging with the culture it’s borrowing from. It’s a missed opportunity that stings. All that energy spent establishing teen archetypes, and nobody thought to spend a few scenes actually honoring the source material or having the expert be representative of the region?

Once the mythology kicks in and the kills start stacking up, the film has its moments. Two of the death sequences are legitimately impressive. One involves a piece of body horror with a nasty conceptual twist that I won’t shake easily. Another is a satisfyingly brutal riff on a concept we’ve seen before, but executed with enough commitment that it works. The practical gore effects land with real impact when they appear. The problem is that there aren’t a lot of opportunities for these old-school methods with most of the effects in the 97-minute film.  These CGI-heavy sequences feel noticeably slicker and less convincing, ragdoll physics and all.

And that’s where Whistle loses me. The third act doesn’t just stumble, it unravels. Egerton seems to lose the thread entirely, and logic problems start piling up faster than the body count (surprisingly low for an R-rated film in 2026). Characters make decisions that no actual teenager would consider making, even by horror movie standards. Percy Hynes White appears as Noah, a menacing youth pastor slash drug dealer, a character who adds virtually nothing to the story beyond padding the runtime and setting up an illogical final stretch. Also, while I’d love to call a moratorium on horror endings that aren’t really endings but are just thinly veiled sequel setups, this one is especially bold about it. Let’s just say that fans of a certain profitable 2024 horror sequel probably won’t be grinning when they see where this one lands.

Leslie Kavanagh‘s costume design deserves a mention. Each teen’s wardrobe feels specific and real, with small details that give the clothes a worn-in authenticity you don’t always see in horror aimed at younger audiences. Production designer Jennifer Spence builds convincing spaces, teen bedrooms that look lived in, a high school that feels institutional, and a Harvest Festival sequence (featuring a maze so gigantic you wonder what the operating budget is for the small town) that injects deep reds and oranges into an otherwise cold palette. (Why do horror films always have Harvest Festivals? Nothing good ever comes from a Harvest Festival.) Editor Nick Emerson contributes some sharp cuts during a chase through the labyrinth and the climax, though elsewhere the pacing doesn’t always help a script that’s already losing momentum.

Whistle isn’t a disaster. It puts in the work early, it has a lead performance that deserves a better vehicle, and it delivers a couple of kills that devoted gorehounds will be talking about. But it leans so close to the films that came before it, borrows so freely and returns so little, that calling it anything more than serviceable feels generous. There’s a chilling idea buried in here, if death can reach one young person, imagine what happens when it hits an entire room, but the film is too busy setting up franchise potential to sit with its own premise. The whistle calls. Whether you answer is up to you.