The Devil's Mouth

Summarize Fact Check

College friends Sara, Max, James, Adrienne and Greg are on a holiday in Thailand. Sara and Max are close friends but Sara often finds her opinions overruled by Max's controlling personality and struggles to stand up for herself. While the group are partying on a yacht, Sara is left behind in the water and is stung badly by a school of jellyfish. Sara forgives Max even though it was her fault the yacht left without her. That night a sea turtle washes ashore with a large bite in its lower body.

The next day the group decide to tour a set of underwater caves called "The Devil's Mouth". They meet tour guide Wat who Max, feeling guilty about leaving Sara behind, secretly tips him to keep a close eye on Sara. Sara finds out, feeling infantilized.

The group explore the caves with Max forcing Wat to take them through a more difficult route. Along the way, they discover freshwater flooded into the caves, killing saltwater wildlife when they came in contact with the freshwater. Adrienne cuts her leg on a rock and Wat tells the group that they have to end the tour immediately. Max refuses to cut the exploration short and they all continue to the next cave.

Sara discovers the diver supervising the group has been attacked. Finding a shark tooth embedded in the divers damaged mask, Wat insists the group leave the cave. Max refuses to leave without a concrete plan and an argument erupts amongst the group. Wat abandons the tourists. A shark suddenly attacks the group, killing Greg. James tells the survivors that the shark is a bull shark, capable of living in saltwater and freshwater environments, hence why it didn’t die like the rest of the saltwater wildlife when it got swept into the string of caves. The group seek shelter on a cliff face, where Adrienne falls into the water and is also killed by the shark. Consulting Wat's map of the cave system, Sara plans out an escape route but Max ignores her idea and demands they take a different route. Meanwhile the shark catches up to Wat and kills him.

The survivors take Max's route, pursued by the shark through a set of underwater tunnels. As they escape to an air pocket, James gets trapped by a falling rock and drowns. Sara and Max resurface and discover they have gone in a circle, taking them back to where the shark initially attacked them. They once more attempt to go through the main route, but the shark notices the light from Max’s headlamp. Max and Sara climb out of the water. The shark rams into the wall that Max clings to, causing a part of the cave to collapse, blocking their exit and breaking Max’s hand. Sara attracts the shark with a flare and throws it into the shark’s mouth, injuring it. Max faints and Sara brings her back to the rocks in the centre of the initial cavern again.

Sara confronts Max and finally takes charge, suggesting they wait until the tide comes in so they can escape through a gap in the cave to the ocean. Sara has a dream about abandoning Max. Sara and Max agree that Max cannot make the climb with her broken hand, therefore Sara will make the climb and get help. The tide comes in and Sara successfully climbs to the gap and is preparing to leave when Max, panicking, also begins to climb but is unable to do so due to her injured hand, resulting in them tying a rope around themselves to help Max. As Sara tries to rescue her, the shark kills Max.

All alone in the cave, Sara is reminded of Wat's warnings about the unstable cave walls. Using her remaining tools, Sara tricks the shark into attacking her, managing to pull a chunk of the cave down, crushing the shark to death. Sara climbs out of the cave and looks out at the ocean, covered in blood and screaming triumphantly.

• Kathryn Newton as Sara McKenna
• Lana Condor as Max Leviton
• Gavin Casalegno as Greg
• Nico Hiraga as James
• Tommi Rose as Adrienne
• Tayme Thapthimthong as Wat

In December 2019, Apex, written by Aja Gabel and Myung Joh Wesner, was featured on the Hollywood Black List of the most liked unproduced scripts.^[5] In May 2023, it was announced that Jeff Wadlow would direct the film, retitled The Devil's Mouth. Producers include Thunder Road Films' Basil Iwanyk and Erica Lee, and Wadlow.^[6] Two years later, in May 2025, it was announced that Amazon MGM Studios and Lionsgate Films would co-produce the film. Kathryn Newton and Lana Condor signed on to star.^[7] In August, Gavin Casalegno, Nico Hiraga, Tommi Rose, and Tayme Thapthimthong joined the cast.^[8] The roles were physically demanding for the actors, with Wadlow saying that "the rock climbing, diving, underwater work, breath holds, getting dragged around on winches, that was all them".^[9]

The script was initially set in Mexico but the entire film was ultimately shot in Thailand, with Wadlow rewriting the script. Wadlow wanted the vacation to "look awesome and fun, and the location seem beautiful and appealing…I wanted it to be obvious why they’re on the trip. It’s an amazing place to visit. Then I wanted to go into real caves that were mysterious and beautiful and not foreboding at all. I wanted the audience on the adventure". Principal photography took place in freshwater caves that are ordinarily used for training by rescue divers, as well as on two sound stages.^[9] Filming locations included Krabi province, Chiang Mai and Bangkok, Thailand, and took eight weeks and was completed by September 2025, with James Kniest as the cinematographer.^[10][11][12]

Bear McCreary composed the score for the film.^[13]

It was released on Amazon Prime Video on July 29, 2026.^[14]

On the review aggregator website Rotten Tomatoes, 34% of 38 critics' reviews are positive, with an average rating of 4.7/10.^[15] Metacritic, which uses a weighted average, assigned the film a score of 46 out of 100, based on eight critics, indicating "mixed or average" reviews.^[16]