Apex was also set in Mexico, which only reinforces the suspicion that The Devil’s Mouth uses Thailand largely as exotic set dressing. Gabel and Wesner retain sole writing credits on The Devil’s Mouth and refined the character dynamics and motivations of its leads. Image: Amazon Prime StudiosImage: Amazon Prime StudiosClose Image: Amazon Prime StudiosImage: Amazon Prime StudiosSara’s seemingly nervous and anxious attention to detail gives way to a levelheaded kind of efficiency once the group encounters saltwater fish in a freshwater cave — and realizes something followed the storm surge inside. That tidbit of trivia gives The Devil’s Mouth just enough scientific plausibility to deliver what seems like a ridiculous premise. One of the cleverest things about The Devil’s Mouth is how it makes a series of monotonous caves look legible.