The film opens with LAFD firefighter Captain Gordon "Gordy" Brewer (Arnold Schwarzenegger) and his fellow firefighters rescuing people who are trapped inside a burning building. After they rescue an old woman, Brewer is caught in an explosion.Cut to a scene where Brewer teaches his son how to play with a toy plane and they plan to meet his son, Matt and wife, Anne in downtown Los Angeles.His wife and son go downtown and wait for Brewer's arrival. Meanwhile a man (who is later revealed as the terrorist) disguised as a police officer parks his police motorcycle in front of the Colombian Consulate and a convoy of Colombian officials and American intelligence agents arrive at the consulate. Brewer arrives and informs the officer that he is there to pick up his family. As Brewer is about to pick up his family, a bomb in the police motorcycle explodes, killing nearby innocent civilians and the officials, including his son and wife. Brewer is then hit by a taxi, injuring him.Later, Brewer is traumatized when he finds out his family was killed in the explosion. The FBI states that 24 people were injured, 9 people are dead including those mentioned above, and the explosion is a terrorism act. Brewer is brought to a hospital and some shrapnel is removed from his body. Suddenly, Brewer realizes that the man he met before the explosion, disguised as a police officer, is the one responsible for the attack and the FBI officers try to stop him.A tape is sent to the U.S. State Department, in which a man pretends to be a police officer calling himself "El Lobo" (The Wolf) claiming responsibility for the bombing, explaining it was in retaliation for America's oppression of Colombia. The FBI believes El Lobo is a Colombian terrorist named Claudio Perrini (Cliff Curtis), the man disguised as a police officer who was there at the time of the explosion.At his home, Brewer receives a message on his phone from Ken Barnett of Lateline and he's invited to tell his story about the incident at the studio and he pounds the phone. Shortly, the news airs the videotape from El Lobo, claiming responsibility for the explosion. Also, it claims that they bombed at least 7 places, including the most recent bombing of the Colombian Consulate in Los Angeles. On the TV, we see only the terrorist in silhouette and a lower-pitched voice saying that the bombing was an act of self-defense against American war criminals, also, if the Americans continue aggression towards the Colombian, they will bring war to them. The terrorist concludes that Colombia is not their country and has to get out now and make a gesture meaning "Sangre o Libertad" ("blood or freedom"). After that, Brewer becomes furious when the reporter mentions the killing of his family and Latin American Solitary Committee Mr. Ortiz calls "collateral damage".Brewer, furious, then breaks into the newsroom and begins wildly whacking everything with a baseball bat. A few minutes later, the FBI officers arrive and incapacitate him with an electric gun. Later, Brewer is brought to the FBI but they don't arrest him because Mr. Ortiz dropped the charges on him. Agent Phipps (Miguel Sandoval) ensures him that The Wolf is back in Colombia.CIA Special Agent Peter Brandt (Elias Koteas), the Colombia Station Chief, is harshly reprimanded for the incident by a Senate Oversight Committee, who promptly terminates all CIA operations in Colombia. Brandt angrily returns to Mompós and meets with his paramilitary allies to plan a major offensive to take down Claudio and his guerilla forces. At Brewer's home, Ed advices to him on how to get inside Colombia.Brewer goes to Mompos, Colombia in order to track down Claudio. First, he gets to the bus and the next morning, the bus suddenly stops because the guerrillas are stopping every vehicle on the road and checking everything on them. In order to not be seen by the guerrillas, all the passengers inside the bus have to get out and hide beside the running bus. As the passengers are running towards the forest, the guerrillas see them running and begin firing at them, killing some of them. Three girls are confronted by one of the guerrillas but Brewer subdues him and they escape. The guerrillas pursue Brewer until he outruns the guerrillas by jumping into a river. The guerrillas find Brewer's bag that he left behind before he jumped into the river, containing his passport.Men present a copy of Brewer's passport to Brandt and alerts them of Brewer's presence. At the same time at the guerrilla camp, Roman presents a copy of Brewer's passport to Claudio and they want to capture him and hold him for ransom.Brewer goes to Mompos harbor then to a carnival. Brewer sees a motorcycle about to hit a boy named Mauro but his mother named Selena pulls him out of the way. After that, Brewer is arrested for entering the country illegally.At the prison, he meets Canadian mechanic Sean Armstrong (John Turturro) and asks him for his pass so he can escape the guerrilla zone but he refuses. Later at night, the guerrilla troops alert the prison with a loud horn before they fire a mortar on the prison. Then, Claudio and his fellow guerrilla manage to kill the police officers and free the prisoners. Brewer sees Claudio for the second time. Brewer incapacitates one of the troops and obtains the circular saw they used to free the prisoners. Brewer frees the other prisoners but he will not free Sean unless he gives the pass to him. Sean gives the pass to Brewer and he frees him. After that, Sean tells him he retired as a mechanic and he tells him to get the harbor, once he gets to San Pablo, he will ask for Felix Ramirez (John Leguizamo), a drug runner. Also, he tells Brewer that he is his replacement.Brewer goes upriver and through the mangrove forest. There, he sees the dead men and the indigenous people. Later, the guerrillas stop the boat and he asks them for Felix. Once he gets there, Brewer pretends to be the mechanic and falsely introduces himself to Felix and one of the guerrillas as "Heinrich Beckmann". Brewer and Felix go to a facility where he is hired to fix a generator. Brewer rigs several improvised explosives.Claudio and his troops confront one of the guerrillas about "Beckmann". He did not realize that "Beckmann" is actually Brewer and he made a mistake. The guerrillas force the man to open his mouth with a metal brace and chokes him with a coral snake, killing him. Claudio tells them to find Brewer.Meanwhile, Brewer still continues making improvised explosives. At night, the guerrillas arrive to find Brewer and asks Felix where Brewer is. Brewer sees them and throws a Molotov cocktail right in front of them, destroying the facility in the process. Roman then shoots Felix who dies in front of Brewer, who is hiding under a truck.The truck heads to Claudio's headquarters. Brewer then infiltrates Claudio's headquarters and plants a grenade in the gas tank, but is captured when he tries to prevent a woman named Selena (Francesca Neri) from being caught in the blast radius along with her son, Mauro. At Claudio's home compound, Selena reveals that she is Claudio's wife and that she and Claudio once lost their own child during an attack by American forces, which compelled Claudio to become a terrorist and fight back, while Selena found and adopted Mauro, whose parents were killed in the attack.Meanwhile, Brandt's unit locates Claudio's compound and launches an attack. During the ensuing shootout, Roman and his fellow guerrillas are killed while Selena helps free Brewer. Brewer sees a landmine set in the forest and clears it before they step through. Brewer fights with a man from Brandt's unit until he gets blown up by the landmine. After that, Brewer meets Brandt for the first time in Colombia and he explains that The Wolf is gone to Washington D.C. to blow another building and Selena and her son will come to identify the target.Claudio arrives in Washington D.C, at the same time as Brewer, Selena and her son. They hear the lower-pitched voice-over of the terrorist saying a bomb has been planted in Washington D.C., but it is too late for them to find it. Claudio leaves a briefcase contain a bomb at Union Station, then an old man picks up the briefcase and tries to open it. At Dulles State Department Annex, Selena identifies Union Station as the target. On the pretense of using the restroom, Selena informs the State Department employee to come along and when Mauro refuses to come with her, she becomes irritated. Brewer recognizes Selena making the same gesture and the words "sangre o libertad" as the masked man claiming to be El Lobo made in the tape, and realizes that she was the Wolf all along, with Claudio serving as her figurehead. Brewer goes to find Selena. When the officers raid the old man with the briefcase, it turns out empty.Selena then kills one of the State Department employees inside the restroom by snapping her neck. Brewer sees Selena dialing on her cell phone when he realizes that she was there at the time of explosion in L.A. and she was using a cell phone to activate the bomb.He pursues her but falls short when she enters an elevator and kills a man inside. Furthermore, Brewer surmises the real target is the State Department. Brewer quickly throws Mauro's toy dinosaur, which is carrying a bomb, out a window moments before it explodes.Meanwhile, a second bomb is set inside a truck at the basement.Brandt, realizing Brewer's suspicions, is shot in the head while trying to stop Selena from fleeing the building. Brewer opens the elevator door and jumps down the shaft where Selena is, but she managed to get out before Brewer gets in. Selena then subdues Brewer and she gets out of the shaft. Brewer chases Selena to the basement of the building where she and Claudio ride off through the underground tunnels on a motorcycle. Brewer finds the tunnel control console and shuts the gates, preventing their escape. Brewer cuts open some gas lines along the walls of the tunnel and, as they ride back, Selena shoots at Brewer, igniting the gas. Brewer jumps through a doorway just as the entire tunnel explodes. Selena and Claudio survive the blast, however, Brewer simultaneously. After a short, hand to hand fight, Selena is electrocuted by being tossed on the exposed circuitry of the control panel. Claudio incapacitates Brewer, then just before he detonates the second bomb using his cell phone, Brewer throws an ax into Claudio's chest, finally killing him.In the aftermath, Brewer carries Mauro in his arms as they leave the State Department. A newscast voice-over explains that Brewer will receive the Presidential Medal of Freedom for preventing one of the worst terrorist attacks in U.S. history from taking place.