Set in Louisiana, seven Tulane undergraduates Sara (Sara Paxton), Nick (Dustin Milligan), Beth (Katharine McPhee), Malik (Sinqua Walls), Maya (Alyssa Diaz), Blake (Chris Zylka) and Gordon (Joel David Moore) drive to Sara's family vacation home on a secluded private lake near Lake Pontchartrain. At a local bait shop, Sara encounters her old boyfriend, Dennis (Chris Carmack) and his friend, Red (Joshua Leonard). Dennis and Red make racial taunts to Malik and Maya, his ... more
Set in Louisiana, seven Tulane undergraduates Sara (Sara Paxton), Nick (Dustin Milligan), Beth (Katharine McPhee), Malik (Sinqua Walls), Maya (Alyssa Diaz), Blake (Chris Zylka) and Gordon (Joel David Moore) drive to Sara's family vacation home on a secluded private lake near Lake Pontchartrain. At a local bait shop, Sara encounters her old boyfriend, Dennis (Chris Carmack) and his friend, Red (Joshua Leonard). Dennis and Red make racial taunts to Malik and Maya, his Latina fiancee, but Sara diffuses the situation. Sara drives a speedboat recklessly to the vacation home, attracting the attention of Sheriff Sabin (Donal Logue). He chases her, frightening her friends, but then happily shares a beer with them. He tells Sara he is happy to see her back after a three-year-long absence.
While Gordon tries to seduce Beth and Sara sunbathes, Nick, Blake, Malik and Maya go waterskiing. A shark pursues Malik and attacks him. Nick, Blake and Maya try to rescue him, but he swims back to shore missing his right arm. When Nick swims out into the lake to retrieve his arm, he is stalked and pursued by the shark. Nick barely makes it back to shore. A pre-med student, he stabilizes Malik, then goes with Sara and Maya to take him to a hospital. However, blood dripping from Malik's wound attracts a shark that attacks the boat. Maya is knocked into the water and eaten. The shark then damages the steering column of the boat. It crashes into the gas pump in front of the boathouse, exploding and stranding everyone. Sara, Nick and Malik barely make it to shore. Because their cell phones have no reception and the house has no landline, they cannot call for help.
Dennis and Red arrive and agree to take Beth and Gordon to the mainland. Nick refuses to allow Malik to be moved. On the boat trip, Red suggests the sharks have entered the lake due to a storm surge from a hurricane then offers a more ominous, vague theory that someone put them there. Dennis reveals that he and Red have put the sharks there and feed uppity college students to them. Dennis forces Gordon into the water; he manages to swim to and climb a nearby mangrove tree but is devoured by a mako shark when it leaps from the water and picks him off the trunk. Red and Dennis then feed Beth to cookiecutter sharks.
When Blake tells Malik that Maya was killed by a shark, Malik arms himself with a harpoon and ventures into the water to kill it. His bloody wound attracts a hammerhead shark; he kills it but is further wounded in the process. Nick and Blake pull the shark to shore, and Nick realizes that it wasn't the shark that took Malik's arm. He also finds a camera attached to its belly. Blake decides to take Malik to the mainland on a jet ski. When Malik sees them being pursued by sharks and realizing that Blake can travel faster without him, Malik sacrifices himself. But Blake is killed when an enormous great white shark breaches from the lake and plucks him off the jet ski.
Sheriff Sabin visits Sara and Nick. He gives them soup to calm them, and appears to use his police radio to call for help. Nick passes out. When Sara goes to the kitchen to get a towel, she finds her dog has also passed out after eating the soup Sabin brought. Sara takes a knife and is about to attack Sabin when Dennis disarms her. Dennis and Red take Sara out on their boat, while Sabin takes Nick to the boathouse and prepares to dunk him into the lake where tiger sharks await. Sabin reveals that he, Dennis and Red have been inspired by the Discovery Channel's Shark Week and Faces of Death videos to film and make available to thrill seekers on the Internet live footage of people being eaten by sharks. When Sabin is distracted by the CD player, Nick frees himself then ignites an overturned can of gas. Badly burned, Sabin plunges into the lake and is eaten by the tiger sharks.
Dennis reveals he is still bitter at Sara for leaving him after their last diving date three years earlier. Sara was unnerved by two accidents that occurred that day: her sudden loss of air (and Dennis's apparent lack of concern), and her slashing his face open with the boat propeller when she tried to escape him. After throwing her dog into the lake, Dennis and Red lower her, in a shark cage, into the lake. A ravenous mako shark appears, but so does Nick, who tries to hold Red hostage and force Dennis to free Sara. Instead, Dennis throws a knife into Red, killing him. Nick and Dennis struggle in the water. The mako eats Dennis then attacks the cage. Sara's dog brings a spear to Nick, and he uses it to kill the shark and free Sara. Nick, Sara and the dog swim to the boat. Just as they think they are safe, the great white breaches the surface and lunges towards them.