Plot summary

Nick Hume (Kevin Bacon) is a loving husband and father of two sons, Brendan and Luke. A Vice President for an insurance company, he is passionate about keeping the columns of his accounts balanced and doing everything in a proper order. After a hockey game, Nick and his oldest son Brendan are driving home and flash their headlights at two passing cars with their headlights off. They then make a quick stop at a gas station to get some fuel. While Brendan is getting a smoothie inside, the two cars they passed earlier, containing several street gang members about to rob the gas station, arrive. The station owner reaches for his gun, but is spotted by one of the gang members and shot to death. It is then revealed that a new gang member, named Joe, must prove himself to "become a man", so he slits Brendan's throat with a machete. Nick scrambles after the thugs as they run for their cars, and tackles Joe as he escapes out the door of the gas station. Nick pulls off Joe's mask, but the murderer escapes. Left behind by his gang, he is struck by a car in the middle of the street. Nick rushes Brendan to the hospital, but he dies.Nick soon learns from the District Attorney that if the case goes to court at all, Joe will only get a maximum of a few years in jail for his crime. Nick declines to identify Joe, forcing the D.A. to drop the case. Joe, now a free man, becomes the target of Nick's revenge. That night, Nick goes over to the apartment complex which he has tracked them down to, and attacks and stabs Joe to death.The gang, led by Joe's sadistic older brother Billy, wants revenge for the murder of one of their own. After ruling out other suspects, the gang begins to track Nick down. A few days later, Billy and his entire gang attempt to kill Nick outside his office in a brazen daylight attack on the street and a chase ensues. Nick is able to escape, killing a second gang member in the process during a fight atop the roof of a parking garage. The police figure out that Nick has started a war with the gang, but without proof, do not arrest him. When Billy calls Nick's house and threatens to kill his family, they are given police protection. But that very night, the two officers watching over the Humes family are killed, and the gang members make their way inside, where they shoot Nick, his wife Helen, and his younger son Luke.Nick survives to wake up in the hospital. He learns that Luke is also alive, although in a coma, but his wife has died. He pays a short visit to his son where he tells his comatose son that life does not add up in neat columns as he always thought it did. He tells Detective Wallis (Aisha Tyler) that "it was never going to balance." She replies, "What did you say?" "The equation," he says. "Sometimes it's just chaos." Under police protection, he escapes from the hospital out his son's hospital window.The next morning, Nick empties all of bank accounts for cash and asks Owen, one of his co-workers, to track down a phone number the gang called him from. At the Four Roses bar, Nick roughly persuades the bartender to provide him with one of the gang members' location and a place where he can buy guns. He pays a visit to Bones (John Goodman), a shady auto mechanic who maintains a black market gun shop. Using all his cash, Nick buys a .357 Magnum revolver, a Colt .45 semi-automatic pistol, and a double-barreled 12-gauge shotgun along with amuntion and instruction booklets. It is here that Bones reveals to Nick that he is Billy and Joe's father, but Bones lets Nick go for he thinks that Billy should reap his consequences for acting on his own without his father's permission.Preparing for battle on what may be a suicide mission, Nick roughly shaves his head and dons his son Brendan's black leather jacket. Nick tracks one of the gang members to his apartment, where he forces him to reveal where the rest of the gang is. He then coerces him into calling Billy, and then shoots him point-blank while Billy is listening.Meanwhile, Bones drives down to a local freeway underpass to warn Billy of Nick's plans, cursing him for his continued screw-ups, but Billy shoots and kills him. Billy then takes his father's car and heads back towards the gang's headquarters, "The Office;" an abandoned hospital which serves as the gang's hideout and place where they grow and manufacture drugs such as marijuana and crystal meth.Nick takes one of the gang members' cars and seeing a van parked outside their building, he rams it with the car he is driving, splitting the van in half and killing the gang member inside. Entering "The Office," he uses the shotgun to quickly kill another gang member and chases down a third. He shoots him in front of a window with his shotgun, and the man is blasted through the window. Two more gang members show up and chase Nick up a staircase. Nick wounds one from the floor above with his .45 pistol, and finishes him off with his shotgun.Billy arrives to find Nick is already there. He finds practically all of his gang dead (several members killed off-camera by Nick during the gun battle). Upstairs, Nick and another gang member exchange shotgun blasts through a wall, and the gang member dies after getting hit. Nick enters what appears to be a former church sanctuary, filled with blood-red light by the red stained glass. Billy appears and shoots Nick in the side, who returns fire and wounds Billy in the chest. Billy's right hand man, Bodie (Edi Gathegi), appears and shoots Nick through the neck from behind, and Nick whirls, killing him with a shot to the head. Billy and Neck exchange further shots until both run out of ammunition. They sit together, exhaunsted and bleeding, on a church pew. Billy tells Nick, "You look like one of us. Look what I made you." Unmoved, Nick produces the .357 revolver from his jacket and, cocking it, asks Billy, "Ready?" Billy sighs. Sometime later as dawn begins to break, Nick staggers from the building alone where it is assumed that he killed Billy.Nick returns home in the gang's Mustang, parking it on the front lawn of his house. Dragging his shot leg and gripping a bandanna to his wounded neck, with blood staining his mouth and chin, he turns on the TV to watch a video of a family celebration. The police arrive and the detective tells him that his son started moving, and that he'll probably make it through. Nick shows a sign of relief and looks back to the TV. It shows Luke, Helen, Nick and Brendan singing on the couch. Nick slumps over, bloody, his head shaved and scarred, and his eyes drop shut.