Shark in a Cave: 'The Devil's Mouth' Trailer Pits Kathryn Newton Against a Freshwater Nightmare
A new shark horror movie has surfaced, and this time the terror is underwater, underground, and very, very real. The Devil's Mouth, an upcoming survival horror thriller from Lionsgate and Thunder Road Films, just released its first trailer — and it looks like a claustrophobic twist on the creature-feature formula that horror fans won't want to miss.
Streaming exclusively on Prime Video beginning July 29, the film follows five college friends on a backpacking trip through Thailand whose adventure turns catastrophic when they become trapped inside a submerged cave system with a deadly predator. As oxygen runs thin and the water rises, old grudges surface alongside the creature stalking the flooded tunnels.
From the Black List to the Big Screen
The Devil's Mouth has been in the works for years. The screenplay, originally titled Apex, landed on the prestigious 2019 Hollywood Black List — an annual survey of Hollywood's best unproduced screenplays. Written by Aja Gabel and Myung Joh Wesner, the script caught the eye of Thunder Road Films' Basil Iwanyk (John Wick, Sicario, The Contractor) and Erica Lee, who saw the potential for a taut, character-driven survival thriller.
The project landed at Lionsgate, and Jeff Wadlow — director of Cry Wolf, Truth or Dare, Fantasy Island, and last year's Blumhouse hit Imaginary — came aboard to direct, also co-wrote the final draft. Wadlow has built a career on high-concept horror with a sense of fun, and from the looks of the trailer, The Devil's Mouth leans into that energy: big scares, beautiful locations, and a monster that doesn't play fair.
A Stacked Cast Headed for Trouble
Leading the charge is Kathryn Newton, who continues her impressive genre run following Abigail (2024), Lisa Frankenstein (2024), and the HBO series Big Little Lies. She plays Sara, the de facto leader of the friend group, whose instincts may be the only thing keeping everyone alive.
Opposite her is Lana Condor (To All the Boys I've Loved Before, Moonshot) as Max, bringing a sharp, grounded energy to the group dynamic. The ensemble also features Gavin Casalegno (The Summer I Turned Pretty), Nico Hiraga (Booksmart, Moxie), Tommi Rose (The Girl Who...), and Tayme Thapthimthong as Wat, a local guide whose knowledge of the caves becomes invaluable.
The casting gives the film a solid foundation: these are actors who can sell the terrified-banter-between-screams dynamic that makes survival horror work. When the characters have chemistry, the stakes feel real — and this group looks like they have it.
The Setup: A New Kind of Shark Movie
The trailer sets up a familiar but effective premise: five friends on a "trip of a lifetime" through Thailand stumble into a submerged cave system that has recently flooded. One of them asks the question everyone is thinking: "How is there a shark in a freshwater cave system?" — and the answer, as far as we can tell, involves flooding that has opened underwater connections to the sea.
The real-life geological backdrop adds a layer of authenticity. The film shot on location in Thailand — specifically Krabi province, Chiang Mai, and Bangkok — over eight weeks, wrapping by September 2025. Cinematographer James Kniest captures both the beauty and the menace of the underground environment, while composer Bear McCreary (God of War, The Walking Dead, The Lord of the Rings: The Rings of Power) provides the score, which should give the film a muscular, emotional backbone.
What to Expect
The shark subgenre is having a moment — and The Devil's Mouth looks like it's carving its own corner. Rather than open ocean or coastal waters, the film traps its characters in an enclosed, labyrinthine space where escape isn't as simple as swimming to the surface. It's part survival thriller, part creature feature, part psychological pressure cooker.
Wadlow's track record suggests the tone won't be relentlessly grim. His horror films tend to understand when to let the audience breathe — and when to pull the rug out. The Apex script was reportedly a tense, contained thriller in the vein of The Descent but with a marine predator. Comparisons to Jaume Collet-Serra's The Shallows or Alexandre Aja's Crawl are reasonable, though the cave setting gives The Devil's Mouth a distinct visual and atmospheric identity.
The Rising Tide of Shark Horror
Shark movies have been a reliable horror subgenre since Jaws, but the last few years have seen a resurgence of high-concept entries. The Devil's Mouth arrives as part of a broader wave — joining everything from deep-sea survival tales to this year's more over-the-top entries. What sets this one apart is the specificity of its setting: freshwater caves, tight quarters, and the constant threat of drowning alongside the shark attacks.
It also benefits from a strong creative pedigree. Thunder Road Films knows how to produce lean, muscular genre films. Lionsgate has deep experience in horror distribution. And Prime Video gives it a global streaming launch, meaning horror fans everywhere can check it out on day one.
Conclusion
The Devil's Mouth looks like a tightly wound summer horror thrill ride. With a strong cast, a proven director, a script that was one of Hollywood's most promising unproduced specs, and a location that brings fresh terror to the shark genre, it's one to mark on your calendar.
The trailer teases narrow underwater tunnels, rising panic, and a predator that has the home-field advantage. If the film delivers on the premise, it could be one of the sleeper hits of the summer.
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