Jim Bickerman rides out of the Lake Placid nightmare with heavy scars—an eye patch, a hook, and a wooden leg—setting the stage for a new chapter in Black Lake, Maine. He teams up with another mercenary, Beach, and together they haul in a female giant crocodile. Their plan quickly spirals into danger when two scientists crossbreed its blood with a female giant anaconda to forge a Blood Orchid serum, a move that promises power but invites catastrophe. The crocodile breaks free, flaming chaos in its wake: it kills a scientist, frees a pair of anacondas, and then detonates the truck, tearing a hole in the electric fence that holds the reptiles. Miraculously, Beach, Jim Bickerman, and one scientist survive, but a small crew of crocodiles slips away into the night.
The danger escalates as the crocodiles hunt for meals. One predator snatches Daphne Mailer and her boyfriend, another crocodile dispatches the remaining scientist, and hatchlings surge into the world, crushing a poacher beneath their tiny, toothy bodies. The reptiles migrate toward Clear Lake, dragging along the ominous presence of the anacondas in their wake. Reba, now the sheriff of Black Lake, calls in U.S. Fish and Wildlife Service officer Will "Tully" Tull to help contain the breakout. At the same time, Delta Gamma sorority sisters—led by Tiffani and Amber—arrive at Clear Lake, joined by two fraternity brothers, Brett and Andrew. The group also includes new members such as Margo and Bethany.
The mood darkens as the crocodiles begin feasting on the sorority party, taking Amber and then targeting other wakeboarders, including Heather as the waves churn with fear. The survivors scatter into the forest, hoping to reach the safety of their cars, though the keys lie uselessly on the beach while a crocodile tears through the group, devouring Cassie in a brutal moment. The chaos intensifies as a car is crushed and a wakeboarding Heather is swept into danger. Deputy Ferguson coordinates evacuations as the town reels from terror.
In New York, Sarah Murdoch, the ruthless daughter of the late Peter "J.D." Murdoch and CEO of Wexel Hall Corporation, assembles a plan to finish her father’s work. She leads a rescue team that includes Beach and Jim Bickerman, along with two mercenaries, in a bid to capture the female anaconda before it lays eggs. The mission is brutal from the start: one mercenary is mauled by a crocodile, forcing Beach to take drastic action. Tully and Reba face an equally lethal challenge as a crocodile attacks them, and then a hungry anaconda crushes it before flying into a fiery explosion.
The pursuit takes them back to the water as Bickerman falls overboard, dragged under by a crocodile, while the other mercenary falls to an attack from the advancing anaconda. Tully and Reba press on, ultimately killing the second anaconda and rescuing Bethany, Margo, and Jane. They regroup with Ferguson just as Sarah and Beach arrive on the scene. They witness two crocodiles feasting on a male anaconda, but the female anaconda appears, killing a crocodile and then turning on Beach, consuming him alive. Beach sacrifices himself by detonating a grenade to kill the very anaconda that swallowed him, deal and a devastating blow to Sarah’s plans. Sarah is arrested, and Bickerman—still alive—emerges from the lake, laughing maniacally.
The final threat lingers as one last crocodile surfaces, only to be finished off by Reba and Tully. In the nest of eggs laid by the female anaconda, a hatchling emerges with an unusual, crocodile-like trait, hinting that danger may yet endure in Black Lake.
