The Devil's Mouth Review: A Horror Gem

The setup is deceptively simple: six college friends - Sara (Kathryn Newton), Max (Lana Condor), James (Nico Hiraga), Greg (Gavin Casalegno), Adrienne (Tommi Rose), and the archetypal reckless boyfriend Ryan (Harrison Luna) - take a celebratory trip to Thailand’s limestone karst country. Guided by the stoic Wat (Tayme Thapthimthong), they ignore local warnings about monsoon season and venture into a sprawling, unmapped cave system. When a flash flood seals their exit, they’re forced deeper underground, where they find a pocket of air - and the nest of a large, amphibious predator that has evolved to hunt in the dark.

What elevates the script is how it threads the survival horror through the group’s existing fractures. Sara and Max are ex-best friends with unresolved jealousy; Greg is nursing a crush on Adrienne, who is dating the loudmouthed Ryan; James is the comic relief who quickly loses his charm. As the air thins, so does their patience. The predator - a blind, eel-like creature with a mouth full of needle teeth - is less a character and more a ticking clock. The real antagonist is their own history, which flares up in moments of selfishness and betrayal.

Wadlow, known for his work in genre mishmash like Kick-Ass 2 and the Truth or Dare remake, here proves he can handle sustained tension. He wisely keeps the creature mostly in shadows, using the headlamps’ erratic beams and the murky water to create a constant sense of spatial disorientation. The camera lingers on tight squeezes, and you’ll find yourself holding your breath during several extended underwater sequences. The sound design is the MVP - the drips, the distant rumbles of shifting rock, and the high-pitched clicks of the predator are genuinely unsettling.

Newton continues to prove she’s one of the best scream queens of her generation, grounding Sara with a frightened but pragmatic intensity. Condor’s Max is the emotional anchor, and their fraught reconciliation feels earned. Casalegno’s Greg is a standout as the silent, brooding type whose hidden competence saves lives, while Rose does a lot with a thankless role as the increasingly hysterical Adrienne. The script doesn’t give Thapthimthong enough to do - he’s the wise guide who gets sidelined - but his presence lends an authenticity to the setting.

The film’s biggest flaws are structural. The opening 20 minutes are a bit rushed, glossing over character introductions with clumsy exposition. The third act also suffers from a classic horror trope: characters make illogical choices just to prolong the chase. However, the pacing is relentless once they’re trapped. There’s no breather, no mercy. The emotional beats hit harder because the actors commit fully to the panic, and Wadlow doesn’t undercut the horror with quippy one-liners. This is a grim, wet, and grueling experience, and that’s exactly what it should be.

Pros

• Stellar leading performance from Kathryn Newton, who conveys terror and resolve in equal measure.
• Masterful sound design and underwater cinematography create genuine claustrophobia.
• The creature is used sparingly but effectively, never over-explained.
• Strong ensemble chemistry that makes the interpersonal conflicts feel real.
• A tight, no-nonsense runtime that avoids bloat.

Cons

• The first act feels rushed; we don’t get enough time to care about the group before the danger starts.
• Some character decisions in the climax are frustratingly idiotic.
• The supporting Thai characters are underwritten and serve as plot devices.
• The ending, while satisfying, feels a bit too neat given the preceding chaos.

The Devil’s Mouth is a nasty, effective little thriller that understands that the scariest monsters are the ones we carry with us. While it doesn’t break new ground, it executes its premise with skill and sincerity. The film’s real triumph is making you feel every scrape of rock and every desperate gasp for air. It’s a perfect pick for a hot summer night when you want to feel cold, trapped, and terrified - in the best way possible. It won’t redefine the genre, but as a character-driven creature feature, it’s a welcome bite. A strong 3.5 out of 5 stars.