Seven Tulane University undergraduates – Sara, Nick, Beth, Malik, Maya, Blake and Gordon – drive to Sara's family vacation home on a private lake. There, Sara encounters her old boyfriend, Dennis and his friend, Red. Nick, Blake, Malik and Maya go wake-boarding when a shark attacks Malik. He is able to swim back to shore – missing his right arm. When Nick swims into the lake to retrieve Malik's arm, he is pursued by the shark, barely making it to shore. Being a pre-med student, he stabilizes Malik, and they all take him to the hospital. Blood from Malik's wound attracts a shark that attacks the boat. Maya (Malik's girlfriend who he was about to propose to) is knocked into the water and eaten. The shark damages the steering column of the boat, causing it to crash in front of the boathouse. Sara, Nick and Malik make it to shore. Dennis and Red arrive and agree to take Beth and Gordon to the mainland. During the boat trip, Dennis reveals that he and Red put the sharks in the lake and feed college students to them. Dennis forces Gordon into the water by shooting him; he swims to a mangrove tree but is devoured by a bull shark. Red and Dennis force Beth to strip down and feed her to cookiecutter sharks. Malik arms himself with a harpoon and ventures into the water to kill the shark that killed Maya. His wound attracts a hammerhead shark; he kills it but is further wounded. Nick and Blake pull the shark to shore, and Nick finds a camera attached to its belly. Blake decides to take Malik to the mainland on a jet ski. When they are pursued by sharks, Malik sacrifices himself and later Blake is killed by a Great white shark. Sheriff Sabin visits Sara and Nick and gives them soup, which makes Nick and Sara's dog, who has also eaten the soup, pass out. Sara hears Dennis and Red speaking from Sabin's radio, describing Beth's death. Dennis and Red then appear and take Sara to their boat, while Sabin prepares to dunk Nick into the lake, where sand tiger sharks wait. Sabin reveals that he, Dennis and Red have been inspired by the Discovery Channel's Shark Week and Faces of Death videos to film people being eaten by sharks. Nick is able to break free and ignite a can of gas. Badly burned, Sabin plunges into the lake and is eaten by the tiger sharks. Dennis reveals he is bitter at Sara for running him over with a jet ski, damaging half his face a while back. Red throws her dog into the water and soon after Dennis calls up Carl, the guy from the bait shop, telling him to release another great white shark, Dennis and Red lower her into the lake in a shark cage. As Dennis is about to release her, Nick arrives and takes Red hostage. After a scuffle during which Dennis kills Red in order to catch Nick offguard, Nick shoves Dennis into the water and tries to set Sara free but Dennis appears and tries strangling him. Nick escapes as a great white shark devours Dennis. Nick kills the shark and frees Sara. Nick, Sara, and Sara's dog swim to the boat, having survived. A distance away, a great white shark breaches, signifying that sharks remain in the lake

When Bobby Saint and Mickey Duka meet with European arms dealer Otto Krieg at the Tampa, Florida seaport, the FBI intervenes and Saint is killed while Duka is jailed. "Krieg", supposedly killed in the shootout, is actually undercover FBI agent and former U.S. Army Delta Force operator Frank Castle. Shortly thereafter, he retires from the FBI and attends a family reunion at his father's oceanside home in Aguadilla Bay, Puerto Rico. Tampa crime boss Howard Saint is enraged by the death of his son, and with right-hand man Quentin Glass bribes the FBI for confidential information about "Krieg". Saint orders Castle murdered, and Saint's wife, Livia, demands Castle's entire family be killed as well to "settle the score". At the reunion, gunmen including Glass and John Saint, Bobby's identical twin, kill most of the extended family. Castle and his father kill several of the attackers before Castle's father is killed. Castle's wife and son try to escape in a Jeep, but Saint runs over them with a truck, killing them. Castle, shot in the chest and blown off a pier in an explosion set by Glass, survives and is nursed back to health by a local fisherman, Candelaria. Once recovered, Castle goes to Tampa and takes refuge in an old tenement where three young outcasts — Dave, Bumpo and Joan — live. Castle abducts Duka, who fearfully gives up information about the Saints — whom he, too, hates, and so willingly becomes Castle's mole. Castle starts exacting revenge on the police and FBI agents who have been bribed to close the investigation of his family's murder. In the process, he sabotages Saint's money-laundering business and severs Saint's partnership with Cuban mobsters the Toro Brothers, and starts tailing Livia and Glass, whom he learns is a closeted homosexual. Saint, realizing Castle is alive, sends two assassins to kill him. Castle kills the first, guitar player Harry Heck, by shooting a ballistic knife into Heck's throat. The second is "the Russian", a behemoth who beats Castle in a brutal fight but is defeated when Castle throws boiling oil in his face, blinding him long enough for Castle to throw him down a staircase, breaking his neck. Moments later, Saint's men arrive, led by Glass and John Saint. Dave, Joan and Bumpo hide Frank and refuse to tell Glass where he is, despite Glass sadistically pulling out Dave's multiple facial piercings with a pair of pliers. They leave a man behind to kill Castle upon his return, but Castle kills him once Glass and the others are gone. With assistance from Mickey, Castle manipulates Saint into believing Glass and Livia are having an affair. Saint, unaware Glass is gay, and believing Livia to be capable of cheating on him, kills them both personally, neither of them knowing why. Castle attacks Saint's headquarters, the downtown Tampa nightclub Saints and Sinners, killing many of Saint's henchmen. He kills John Saint by having the crime boss' son hold an eight-pound, trip-wire activated grenade until his arm wearies and the grenade explodes, killing him. Castle wounds Howard Saint with a pistol when Saint attempts to shoot him in the parking lot of the nightclub. Castle then ties Saint to a slow-moving car, but not before revealing that Glass and Livia were not having an affair. Several hidden bombs go off, and the destruction and wreckage culminate in the shape of the Punisher's iconic skull. Later that night, Castle returns to his apartment and prepares to commit suicide, but after a brief vision of his wife, decides to continue his vigilante mission against others who in his mind deserve punishment. Before departing on his next mission, he leaves most of Saint's money for Bumpo, Joan and Dave. On the Sunshine Skyway Bridge, he vows, "Those who do evil to others — the killers, the rapists, psychos, sadists — will come to know me well. Frank Castle is dead. Call me the Punisher."

The Special Weapons and Tactical division of the Los Angeles Police Department (LAPD) is the most honored and respected unit in the entire world. When two cops, Officers Jim Street and Brian Gamble foil a bank robbery holdup by shooting a female hostage, the two are kicked out of SWAT, stashing them into the "gun cage". Six months later, Street's ex-friend Gamble is gone, and so is his future until one day an cop arrives to give Street a second chance at redemption by putting him back on SWAT. That man is veteran Sergeant Dan 'Hondo' Harrelson, an Old School boss cop who think second chances are just a-OK. Now Hondo, Street, and the new SWAT team consisting of: Michael Boxer, T.J. McCabe, Deacon 'Deke' Kaye, and a female cop, Christina 'Chris' Sanchez, has a big mission: escorting Alex Montel, a international fugitive and serial killer to a federal prison in the California desert, but problems get in the way along the way including two fake cops breaking the detainee out, offering $100 Million on live TV to street gangs who can get Montel out, and worse, Gamble and McCabe getting him to safety. Can the SWAT team take down Montel and can Street finish the score with Gamble?