After a 20-year hiatus, Laura Le Crois ([elena-lyons](../actor/elena-lyons)) finds herself returning to her childhood home in the wetlands of Louisiana, driven by the sudden disappearance of her father, Pappy ([phillip-beard](../actor/phillip-beard)). Her return is complicated by the fact that her ex-husband, Charles LeBlanc ([mark-sheppard](../actor/mark-sheppard)), a zoologist with questionable motives, is trying to purchase the wetland. Charles appears to have a hidden agenda related to the wetlands and is searching for her father, who might hold the key to his plans.
As Laura navigates the dangers of the wetlands, she encounters Matt ([gabe-begneaud](../actor/gabe-begneaud)), a young man preparing to be drafted into the Marines, and his girlfriend Mandy ([lacey-minchew](../actor/lacey-minchew)). Matt asks Laura to give him and Mandy a tour of the area, so he can propose to her later that evening. Reluctantly, she agrees, and the trio sets off on a small motorboat for what seems like a peaceful day. However, this peaceful day takes a dark turn when Laura witnesses her father being thrown into the water by locals Barry and Larry Boudreaux ([scott-l-schwartz](../actor/scott-l-schwartz)). moments later, her father is attacked and eaten by a pilosaurus, an aquatic reptile thought to be extinct, which adds a terrifying twist to her journey.
The chaos intensifies as Barry and Larry, armed and dangerous, capture Matt and Mandy, knocking Matt unconscious and taking Mandy hostage. Laura, in her attempt to warn them, is knocked out herself by Larry. When the next day arrives, Sheriff Tim Richards ([lochlyn-munro](../actor/lochlyn-munro)), her former partner, along with his younger brother, Deputy Henry ([caleb-michaelson](../actor/caleb-michaelson)), begin investigating the mysterious disappearance of Laura, Matt, and Mandy. Sheriff Tim quickly suspects that something sinister is happening with Charles, who seems overly interested in the wetland and the recent events.
Meanwhile, Laura, Matt, and Mandy are discovered to be held captive in Barry and Larry’s cabin, which is rigged with explosives. Barry and Larry plan to feed Matt and take Mandy as well as Laura to the pilosaurus. It turns out that Charles’ true plan involves the cloning and captivity of the pilosaurus, intending to use the creature as part of his business ventures. He reveals his intent to sign papers to buy the wetland so he can keep the creature safe and hidden, but Laura soon uncovers that Charles is motivated by greed and the desire to exploit the dinosaur.
As the situation spirals further out of control, Barry and Larry's plans are thwarted when Mandy creates a distraction by detonating explosives in the cabin. Laura, showing resourcefulness and courage, stabs Larry in the eye with a pen, enabling her, Mandy, and Henry to escape. In the chaos, Larry is consumed by the very creature he aimed to exploit. Barry pursues them, shooting Henry in the leg, but they manage to reach Laura's boat. Unfortunately, the pilosaurus destroys the boat, forcing the group to seek refuge.
The group faces multiple dangerous encounters. Henry bleeds out from his wound, ultimately succumbing to his injuries, while Laura and Mandy scramble to find help. They come across two fishermen, hoping one might have a phone, but the pilosaurus kills both fishermen before they can be rescued. Barry re-enters the picture, recapturing Mandy and then calling Charles to report failure in capturing the girls. On the way to another cabin, Barry reveals shocking personal information: he is actually Laura’s half-brother because of a past involving Pappy and his mother.
In a tense climax, Froggy ([paul-wall](../actor/paul-wall)), who is working for Charles and helping him, kidnaps Laura and Mandy. Froggy confesses that his motivation stems from a personal grudge related to Pappy’s past affair. As Froggy attempts to escape with the girls, Sheriff Tim intervenes, causing a traffic crash into the cabin and killing Froggy in a gas explosion.
Finally, Laura, Mandy, and Tim return to the wetland tour site, where they discover the pilosaurus' nest and the sonar device used to attract the creature. Charles arrives, attempting to threaten and capture the group, but Laura quickly realizes his true plans—to keep the cloned pilosaurus as a controlled freak show. As Charles threatens Mandy, [Tim](../actor/lochlyn-munro) disarms him and throws him into the water, where the pilosaurus devours him. With the creature threatening them on land, Lefty, Laura’s mother, [debbie-gaudet](../actor/debby-gaudet), arrives just in time, throwing dynamite into the creature’s mouth, ultimately killing it.
With the threat eliminated, the group, battered but alive, thanks Lefty for her heroic act. The story ends with rescue crews arriving to tend to the injured, and a reminder that even the most hidden dangers can resurface when least expected.
