LionsgateWith a pedigree that includes Snakes on a Plane, Snakes on a Train, and the 1997 Jennifer Lopez-Ice Cube vehicle Anaconda (and its quickly forgotten 2025 reboot), it’s safe to say that giant-snake movies are not the most highbrow of horror subgenres. To be clear, Beware Boiúna doesn’t buck this trend: Although the title character is evoked in terms of “defending” the jungle and “restoring balance” between humanity and nature, her inability to tell the good characters from the bad ones effectively negates any themes the movie might be reaching for in this department. (Unless the message is that all humans must be eliminated if Earth is to survive, which would be pretty badass.) In this case, the giant snake is just a giant snake — which is for the best, actually, because then we can relax and just enjoy the mayhem. An American director like Mike P. Nelson (Wrong Turn, Silent Night Deadly Night) making a survival horror movie set in the Amazon has the potential to be a cultural minefield as well. Nelson manages to sidestep this, largely through a twist in the second act that we won’t spoil here, but takes the movie in a fun new direction leading up to the creature-feature finale. In the meantime, Nelson and screenwriter Alan B. McElroy (Wrong Turn, Halloween 4: the Return of Michael Myers) introduce a cast of characters reminiscent of the scientific exposition team in another jungle classic, Creature from the Black Lagoon. Jessica Rothe spots something scary in the water in Beware Boiúna. | LionsgateIn this case, they’re on a medical mission to treat Indigenous people living in Peruvian Amazonia, in small villages that are hundreds of miles away by boat from the nearest hospital. Various crew members and mentors circle around them, but the key characters here are Alli (Jessica Rothe), a bleeding-heart American medical student, and Lena (Kiana Madeira), a streetwise (jungle-wise?) local working the boat for extra cash. Lena has a secondary motive as well, but that comes in later. First, she and Alli must provoke the wrath of sleazy developer Brennan (Logan Marshall-Green), a classic movie douchebag in the ‘80s-villain mold. After a found-footage style cold open, the first two-thirds of Beware Boiúna are driven by the drama between the human characters, shifting into eco-thriller mode as Brennan chases Alli and Lena’s boat through the jungle. This is fine, in part because of the capable cast and in part because it lulls you into almost forgetting that a giant snake is going to pop up at some point, increasing the jump-scare impact when this hundred-foot queen finally comes crashing through the swamp. Jessica Rothe, Kiana Madeira, and Jaime Newball, also looking at something scary. | LionsgateWhen they do arrive, the monster-movie scenes are very big and very loud — this is probably the loudest movie we’ve seen in theaters all year, louder even than Godzilla Minus Zero. The film’s VFX budget is put to use for a few clear, good-quality shots of Boiúna herself in all her slithery glory. But the majority of the snake attacks are captured with shaky camerawork that makes it all but impossible to follow what’s happening in the moment. Accompanied by a sound mix that’s turned to 11, the effect is equal parts thrilling and painful. Nelson presumably filmed the action this way in order to “hide budget,” meaning that he fudged the details with shaky camerawork in order to disguise the fact that this modern-day B-movie didn’t have enough money to make the snake look good all the time. But there are other ways to approach this problem, from the old-school tricks of Val Lewton to the brief glimpses of the shark in Jaws. To his credit, Nelson did film many of the effects practically, and the carnage that Boiúna leaves floating in her wake does look pretty good. Muddy mayhem in Beware Boiúna. | Fantastic Fest There’s one sequence where the balance of horror elements is just right, in which Madeira falls into a deep pit of soggy mud and struggles to pull herself out as Boiúna slithers closer. It’s a throwback to adventure movies of years past — between this and The Swallow, which also premiered at Fantastic Fest, quicksand is making an unexpected comeback in 2026 — that works because it doesn’t dress up (or obscure) its scares too much. Tense and inescapable, it provides the pure entertainment that the rest of this movie is striving for. But for an unabashed B-movie like this one, achieving the modest ambition of pulling off one killer horror scene is enough. From Lionsgate, Beware Boiúna is now playing in theaters.