Audiences love shark movies. The challenge isn't competing with Jaws; it's finding a fresh way to tell a new shark story that hasn't been seen before.
For screenwriters Aja Gabel and Myung Joh Wesner, that breakthrough came from combining two fears instead of one.
Rather than simply writing another shark attack movie, they imagined what would happen if the cold-blooded killing machine was hunting inside an underwater cave system where there was nowhere to run. That single idea eventually became The Devil's Mouth, directed by Jeff Wadlow, in which five friends explore remote caves in Thailand only to discover that something deadly is stalking them beneath the water. The premise hooked Wadlow before he had even read the screenplay.
"It's not just a shark movie," he says. "It's a claustrophobic horror movie mixed with a shark movie."
But while the high concept got everyone excited, all three filmmakers insist that's not what makes the film work. Beneath the shark attacks and confined caves is a story about a complicated relationship between two besties, whose emotional wounds become just as dangerous as the predator chasing them.
Inspiration From a Vacation
The screenplay's origin began with an unsettling vacation experience. While snorkeling through the cenotes in Tulum, Mexico, Gabel noticed scuba divers moving deep beneath the surface. Because of the water's distortion, they looked less like people and more like strange beasts silently gliding below. "It felt kind of like a massive creature is moving under you," Gabel says.
She shared the experience with Wesner, who immediately joked that the only thing scarier would be discovering there was a shark in the caves. The joke quickly evolved into a screenplay.
At the time, both writers had recently signed with representation and wanted new material. They wrote the script quickly, originally setting the story in Mexico before years of development eventually transformed it into the Thailand-set thriller audiences will see today.
Finding Your Own Shark Tale
There have been dozens of shark movies since Jaws, and it's hard not to compare them to Spielberg's masterpiece. But that wasn't something Wesner spent much time worrying about.
"I just didn't think about it as being anything like Jaws," she says. "This was really a movie about a group of friends and two best friends in particular."
The writers focused on a fractured female friendship to help distinguish the story. Wesner drew inspiration from painful middle-school relationships and the emotional scars that can linger for years. For Gabel, her biggest inspiration was The Descent, the claustrophobic thriller about women trapped underground. "I wanted to write something that felt like it was about the terror of being trapped," says Gabel.
Sometimes combining familiar elements in a way audiences haven't experienced before is the key to writing in a well-trodden genre.
Horror Begins With Character
For Gabel and Wesner, the hardest problem wasn't creating jump scares and inventive kills; it was making the two central characters, Sara (Kathryn Newton) and Max (Lana Condor), likable.
"It remained a challenge throughout the tens of drafts that we did," Gabel says. "That was always a note."
The friendship at the center of The Devil's Mouth is intentionally complicated, even toxic at times. The challenge was helping audiences understand why these women remain so important to each other despite years of emotional baggage.
"We knew the toxic female friendship aspect was so relatable, but it took a lot of drafts to really hone in on moments where you understand why this friendship is also important to them," says Gabel.
Because lifelong friendships are built over years of shared history, the writers couldn't simply have the characters explain everything through flashbacks or dialogue.
"They're not going to be sitting there reminiscing," Wesner says. "So trying to put that on the screen in little interactions was the challenge."
Production Changes Can Be a Gift
One of the movie's biggest improvements happened because of a production challenge. Originally, the film was supposed to shoot in Mexico. But just days before leaving, the studio informed Wadlow that he'd be shooting in Thailand instead.
Initially, he hated the idea. Mistakenly believing that Thai food was full of peanuts, Wadlow was worried he might die due to his intense nut allergy.
Then he stopped himself. One of his personal filmmaking philosophies is to examine why you're resisting an idea. Sometimes the thing you're fighting against is exactly what the project needs.
After researching Thailand's cave systems and remembering the real-life rescue of the youth soccer team trapped in the Tham Luang cave, he realized moving the story to Thailand was actually better. Thailand felt more remote, and a delayed rescue became more believable. The location itself became another character in the story. "It solved a lot of our problems," Wadlow says.
Two Questions Horror Writers Should Ask Themselves
Wesner had some interesting advice for tackling horror. When she sits down to write, she always asks herself two questions: What are the scariest situations imaginable? Who would be the most interesting person to experience them?
"I think about a few really scary images and then what's the most interesting type of person to put in that situation?" she says.
While the external danger (the shark) creates suspense, the internal conflict (the relationship between Sara and Max) creates stakes. Together, they make memorable horror movies. Wadlow also gave advice on the importance of good characters.
"I always talk about the difference between Jaws and Jaws 2," he says. "In Jaws, you're rooting for the characters. In Jaws 2, you're rooting for the shark."
If the audience genuinely cares about the people in danger, every attack becomes more thrilling. For Wadlow, that's the first rule of horror. "You've got to make sure you have characters that the audience is going to love."
The Devil's Mouth is currently streaming on Prime Video.