At the Fantastic Fest premiere of Beware Boiúna, Lionsgate rolled out the scaly carpet, coating the festival’s opening night in the trappings of its jungle-set horror-adventure. A giant snake’s mouth loomed over the entrance to the festival itself, attendees were invited to take photos with a massive live snake, and spring-loaded snakes in a can were at everyone’s seat before the screening began. It all screamed “Hey, we made a fun monster movie about a big snake!” Then the movie started, and most of that goodwill was chipped away over the ensuing 90 minutes. Choppy, meandering, and frustratingly dim (literally and metaphorically), Beware Boiúna squanders a great concept, and swamps the moments it does manage to deliver under loads of narrative and visual murk.
In the section of the Amazon jungle running through Colombia, a group of medical volunteers are hoping to make a difference to the poor locals, and Alli (Jessica Rothe) is determined to prove her worth. She’s just a volunteer, still learning the ropes of this kind of humanitarian aid, but she’s eager, kind, and genuinely yearning for connection, something she specifically seeks out in Lena (Kiana Madeira), the withdrawn, prickly mechanic aboard the boat taking the team downriver.
But even as Alli takes to her work with passion and energy, forces conspire to make things harder. The jungle is crawling with illegal mining operations and exploitative logging camps, which means Alli, Lena, and the rest of their crew sometimes have run-ins with profiteers like Brennan (Logan Marshall-Green), who happens to be working the same stretch of river. When a testy exchange turns into a larger fight, Brennan pursues Alli, Lena, and the medical team deeper into the jungle, where an ancient forest guardian—in the form of a gigantic snake—looms, ready to protect her home.
At least Boiúna, said gigantic snake, is big. Really big. Big enough to capsize boats and rip apart mining camps and squeeze just about anything until it pops like a grape. She’s so big, in fact, that director Mike P. Nelson‘s camera can never quite capture all of her, which wouldn’t be a problem except, the film gets so little of Boiúna as a creature that at times it feels like she may as well not be a snake, just a CGI tentacle that whips stuff around when the plot demands it. The script, by Alan B. McElroy, takes ample time to explain Boiúna’s lore as the steward of the jungle, and we’re never left in doubt as to the scale of the creature (even if there’s not much detail in that department), but once she’s introduced as a threat, Boiúna never takes on much in the way of actual character. While you could charitably frame it as the film’s effort to depict Boiúna as more force of nature than animal, after a while it becomes grating. There’s no sense, at least until the very end, that the snake is aware of what she’s doing beyond mindlessly chomping extras. While that’s fun for a little while, there’s no real menace to it. Boiúna’s role in the story is only to exist.
Which would be fine if we could only see her, or if her presence created a kind of Rorschach test for each of the film’s characters, upon which they could project their emotional arcs. Shrouding your title monster in jungle foliage and river water works for a while, but at a certain point the film needs more, and Boiúna is always shrouded in murk.
The characters around her struggle to fill the void. The cast is clearly game to make a big, sweaty jungle adventure with a giant monster at the center, and Rothe and Madeira in particular bring the kind of absolute commitment that movies like this need, but there’s very little for them to grab hold of. Alli wants to make the world a better place, and Lena has some vague family issues centered on her lost brother, but that’s about all we get. This would also be fine if the film wanted to work from exploitation and action cinema archetypes, playing things big and brassy like creature features of old, but Beware Boiúna feels perpetually stuck between gears, too serious and grounded to be fun, and too uncontrolled to be anything approaching a psychological monster movie.
Still, there are bright spots. When the film actually slows down between snake attacks, Nelson sets up some convincing and gripping set pieces. Whether he’s playing with the idea of Boiúna trapping characters on a boat, tossing people into quicksand, or using human corpses as a means of conveyance, there’s cool stuff here. But Beware Boiúna is too rushed, and too focused on yet another snake jump scare, to let its successes breathe. This is a movie that’s crushed by its own constrictive premise far too quickly, smothering the fun out of itself.
Director: Mike P. Nelson
Writer: Alan B. McElroy
Starring: Kiana Madeira, Jessica Rothe, Logan Marshall-Green
Release Date: October 2, 2026
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