Director Jeff Wadlow warned his cast upfront that “The Devil’s Mouth” would be unlike anything they’d shot before. He told them the film would rank among the most physically demanding projects of their careers, not only because of the underwater stunt work but because even ordinary dialogue scenes would require treading water for hours at a stretch.
The Prime Video horror-thriller, written by Aja Gabel and Myung Joh Wesner and drawn from a script that landed on the 2019 Black List under the title “Apex,” follows five friends whose Thailand vacation turns deadly when they become trapped in a freshwater cave system with a bull shark. Kathryn Newton and Lana Condor lead the ensemble as best friends Sara and Max, with Gavin Casalegno, Tommi Rose and Nico Hiraga rounding out the group. Wadlow said he was drawn to the project by the unusually layered friendship at its center, calling it a nuanced study of two women whose bond fractures under pressure.
Before filming began, both lead actresses questioned the casting. Newton and Condor each felt they might be better suited to the other’s part, timid Sara versus domineering Max, though Wadlow said the finished film convinced him otherwise. He noted that stress between the two characters becomes the story’s emotional center as their situation deteriorates.
Physically recreating an endless cave system required building 13 separate sets across two soundstages, using lighting and set dressing to disguise a single massive structure as dozens of distinct locations. Wadlow praised his cast for performing their own stunts, including winch work and extended breath-holding sequences, without complaint despite spending hours submerged each shooting day.
Off camera, the Thailand shoot brought its own hazards. Condor has separately described being attacked by a monkey during production, while co-star Nico Hiraga said he spotted a shark swimming in open water near the set, and the crew noticed sharks circling Newton during filming on a yacht. Wadlow called the production the hardest shoot of his career. “The Devil’s Mouth” is now streaming on Prime Video.
