Trace McGraw arrives by taxi in Puerto Vallarta, Mexico, already running late for a chance to reinvent himself. A friend lends him a sea-worthy boat and warns that he’ll be out of reach for two months with no reliable mobile reception. Another buddy jokes that Trace is still a captain of the rich and famous, but warns that his papers aren’t in order, pushing Trace to improvise a little, even offering a necklace that’s touted as an aphrodisiac to seal a deal. A wary word about Calderón](/actor/humberto-busto) lingers as Trace sets his sights on a fresh start.
Moments after Trace’s arrival, a surfer is swallowed in a split second by a dinoshark — a predator that moves with the speed of a dolphin and can clear a path through the water with terrifying ease. The brutal incident turns into breaking news reported by Stacy Ramos, whose televised coverage paints a town already skittish about bad weather and the risks of the sea. The shark’s sudden attack foreshadows a menace that won’t be easily contained.
Trace reconnects with old acquaintances, including Pedro, who introduces him to Carol Brubaker and Rita Valdez along with Víctor](/actor/guillermo-ivn). Trace reveals that his last job lacked glory and that he once hit someone in the shoulder, which sent him back home to try his luck anew. Pedro cautions him that snorkeling isn’t a reliable way to strike it rich. Carol’s life in the resort world is busy and ambitious; she’s a Princeton-educated biologist who moved to the coast with plans to expand the family business, and she’s trying to navigate the political tides of local development.
When Carol contacts Mike to regroup their plans, she’s set on balancing work with the needs of the women who will be drawn into their projects. Rita immerses herself in her own inquiry, swimming in the cold, grey waters, unaware that danger lurks just beneath the surface. The rescue patrol arrives too late to save her; Rita’s body is recovered later, leaving Trace to grapple with a personal loss that rekindles old memories.
Carol’s world expands beyond the resort as she contemplates a future where she could lead, direct, and study the local ecosystem. Her outreach becomes personal when Trace reveals that Rita was his first love, and Carol realizes that Calderón is likely to distrust Trace’s motives given the mystery surrounding a missing boat, a stash of marijuana, and a string of coincidences that keep tying Trace to trouble. Calderón dispatches a helicopter to chase the beast, while Trace and Carol find themselves drawn into a perilous pursuit across the canal and open water.
The dinoshark’s appetite throws another woman into peril: Lois](/actor/liv-boughn) is pulled into the sea by a powerful current as a wealthy man, Steve Loggins, tries to charm her. The predator eats him too when he moves to help her, showcasing the creature’s cold efficiency. The hunt intensifies as Trace and Carol plot a trap to study the creature and perhaps capture it alive, aiming to unlock its secrets rather than simply kill it.
Carol turns to science for answers. She tracks down Dr. Frank Reeves, who describes a primordial animal that could still be alive and notes that bones from similar creatures have been found. Reeves agrees to analyze a beacon device discovered in the water, hoping it might yield a genetic profile of the beast if there are any remains to study. Trace pledges to wait for Reeves’ assessment before taking decisive action, but a tense chase soon puts both of them in direct contact with the shark’s path.
Trace’s attempt to photograph the predator is interrupted by guards who suspect him of shady dealings or smuggling. The tension grows as the shark targets a canal and a pair of rowers, one of whom loses their life in the scramble. Jade joins a group of rowers, and the shark snatches a companion as they laugh and flirt their way along the water. A party scene features Dr. Otis, who remarks that it’s hard to believe a living dinosaur could exist, hinting at the scientific debate that has simmered in hushed rooms for years. Dr Simon Otis argues that a creature this large could still survive.
As the crisis escalates, Calderón begins to suspect Trace, blaming the timing of his arrival for a spate of disasters. He orders his team to hunt the creature, and a helicopter chase ends in disaster when the rappel craft crashes after the shark’s sudden leap. Trace urges Calderón to adapt and plan for a bigger, better pursuit.
Meanwhile, Luis, the local bartender, finds himself stuck in a traffic jam near a federal checkpoint. He makes his way toward Punta del Flamenco in an attempt to reach the national park, hoping to help. The dinoshark closes in on Trace and Carol's boat, and a family on shore looks on in fear as the creature claims another victim — a crocodile is disturbed and an innocent child’s toy boat is left adrift.
The town’s tourist attractions, a folk dance troupe, and a sailing race become backdrops to a deadly hunt that tests everyone’s nerve. Carol’s team continues to train the diving group, while a desperate rescue operation unfolds with the rest of the community in the line of fire. The dinoshark’s rampage doesn’t stop; it consumes a jetskier and a parasailor as the crowd watches in horror, and even a nearby jetskier’s video camera records the chaos for posterity.
As the hunt intensifies, Frank Reeves explains that the creature’s only vulnerability lies in its eye. A dramatic confrontation follows: the shark lunges toward Trace on a jetski, Trace launches a grenade in a risky move that wounds the predator but doesn’t finish it. Carol takes aim with a harpoon and hits a vulnerable spot in the eye, finally bringing the dinoshark down. In the aftermath, Trace, Carol, and Eddie](/actor/jack-everest-hite) survive the encounter, while the sea’s surface settles into an uneasy quiet.
Yet danger remains. A new shard of Antarctic ice breaks away from a glacier, and this time it carries several dinoshark offspring — a chilling reminder that the threat could return in greater numbers. The story closes with a somber sense that the ocean still holds secrets, and that the people who live by its edge will carry the memory of this encounter long after the last fin vanishes.
