After local sheriff Kate witnesses her colleague being eaten by sharks in a river, she enlists the help of her friend Carl, who's also an avid hunter, to kill the sharks. Meanwhile, a company retreat is taking place at the river, headed by the company's owner Tanner Brooks. Among the employees are John Pullman, and Tanner's publicist Stella, who have a strong friendship. Three employees are soon killed by the sharks unbeknownst to Tanner, and the other employees, and Tanner prepares to take the entire group river rafting. However, Stella soon confesses to John that Tanner will be keeping all of the people he invited on the trip, and firing everybody else.Kate, and Carl, meanwhile, witness an employee being dragged downriver by a shark while another employee chases her. After both employees end up being killed by the shark, Kate, and Carl discover that the sharks are building dams using human bodies. They manage to blow one up, and go to destroy the other remaining dam. Meanwhile, Tanner, and his employees go river rafting, where John confronts him about his plans. As Tanner prepares to fire John, the sharks attack, killing many people, and leaving only John, Stella, Tanner, and fellow employee Kenny as the only survivors still in a raft while three other employees: Jolene, Ted, and Jorge, manage to reach shore, where they find Kate, and Carl. While Kate, and Carl go to destroy the dam, Jolene, Ted, and Jorge are forced to cross a log across the river in order to reach the nearby ranger's station, although all three are quickly killed by sharks.Back on the raft, the sharks begin dragging the raft towards the dam, and Tanner is soon eaten while Stella uses a bow-and-arrow to detach the line. She then uses several paintball cartridges from an earlier game of paintball to make the arrows explosives. After Stella kills several sharks, Kenny accidentally pops the raft, forcing the three to swim to shore. However, John's foot becomes tied in a rope, forcing Stella, and Kenny to save him, although Kenny is soon eaten by a shark while Stella manages to free a now unconscious John. Kate, and Carl arrive in their boat, and Stella revives John. After Carl is killed by another shark, Stella uses an arrow to blow up the dam. They are soon attacked by one remaining shark, although Stella manages to kill it. As John, Kate, and Stella make their way to shore, another shark is shown stealing a body underwater, hinting that the threat is not over.