On a Los Angeles freeway, William Foster sits in stopped traffic in his worn station wagon. Car exhaust and sounds of screaming children from adjacent vehicles create an intolerable atmosphere. Reaching a breaking point, Foster abandons his car, calling out to an annoyed driver that he’s “going home.” Caught in the same traffic, Detective Prendergast notices Foster's abandoned vehicle and gets out of his car to help a highway patrolman move the station wagon. Soon after, Beth Tavino rushes her daughter Adele back to their Venice home after she hears the phone ring from the street. When Beth answers, no one speaks. The pay phone caller, Foster, hangs up. Wanting to call Beth again, Foster realizes he does not have enough change, so he enters a nearby convenience store and asks to change a dollar bill, but the Korean shop owner insists he must buy something. Foster tries to buy a can of Coca-Cola, but the cost is eighty-five cents, which will not give him enough change for another call. Foster argues with the shop owner over the price and insults his English. The argument becomes physical when the shop owner retrieves a bat from below the counter. Foster wrestles the bat away and uses it to destroy overpriced merchandise in the store. The shop owner watches from the ground as Foster pays fifty cents for the soda, takes his change, and leaves with the bat. At a police station, fellow officers play a practical joke on Prendergast on his last day before retirement. Prendergast receives a call from his wife Amanda, an emotionally troubled woman, who pleads with him to come home. He calms her by singing "London Bridge Is Falling Down.” Seated on an abandoned lot, Foster fixes a hole in his shoe. Two gang members appear, claiming he is on their "turf." He attempts diplomacy, but fights back after one of the gang members pulls a switchblade knife. Foster beats both with the bat, and steals the switchblade. Later, Prendergast surrenders his gun back to inventory as Mr. Lee, the Korean shop owner, arrives to report Foster's attack. He admits to Prendergast that Foster did not steal anything but his bat, and provides a physical description of Foster as a white man in a shirt and tie. On the streets, the beaten gang members drive around in search of Foster. Angie, a friend, pleads with them to go to the hospital instead of seeking revenge. At a nearby payphone, Foster informs Beth that he is heading home to give Adele a birthday gift. Beth reminds him that her house is no longer his as she is no longer his wife. As Foster hangs up, the gang members spot him and spray gunfire, hitting two people. Their car collides with another as they turn the corner. Unharmed, Foster approaches the wreckage, picks up a gun and shoots one of his assailants in the leg. Foster retrieves a bag full of guns from the car and walks away. Meanwhile, Captain Yardley conducts an exit interview with Prendergast. When Yardley asks about his “kids,” Prendergast informs him that his one daughter died. In Venice, Beth explains to a police officer that she has a restraining order against her ex-husband and is afraid he is headed there. Taking a report, the officer confirms that Foster has never actually been violent toward Beth or Adele. Elsewhere, a homeless man tries to swindle money from Foster in a park, but he gives the beggar his briefcase, which only contains his lunch. Foster's only luggage now is his bag of weapons. At the station, the police interrogate Angie about her friends' drive-by shooting. From behind the mirror, Prendergast observes as Angie describes their target, who matches the “white shirt and tie” description provided by the Korean shop owner. Prendergast tries to intervene, but an officer pushes him away from the interrogation room. At 11:33 AM, Foster enters a Whammyburger restaurant and attempts to order breakfast. The cashier informs him that breakfast is no longer served, as it is three minutes past the cut-off time. After the manager refuses to accommodate him, Foster pulls a gun from the gym bag, terrorizing everyone in the restaurant. He finally orders lunch instead of breakfast, only to express dissatisfaction to the frightened onlookers that his food does not look like the advertised meal. At lunch, Prendergast and a friend from the office, Detective Sandra Torres, discuss his decision to retire early. Officer Lydecker arrives before the food, and asks Sandra to join him in investigating the incident at Whammyburger. Continuing on his trek, Foster sees an angry protestor outside of a bank. The man, who is dressed exactly like him, was denied a loan after he was deemed "not economically viable." Next door, Foster buys a snow globe for Adele as police arrest the protestor. At Beth’s house, the police leave because they suspect no immediate danger. Foster again calls from a payphone but gets a busy signal. After an angry man waiting for the phone complains that he is taking too long, Foster destroys the phone booth with a machine gun. Sandra phones Prendergast from Whammyburger to inform him that the descriptions given by witnesses match his “white shirt and tie” suspect. Foster enters an army surplus store and Nick, the owner, readily helps him while insulting two gay customers. When Foster goes into a dressing room to try on boots, Sandra enters in search of him. Nick denies seeing a man that fits Foster’s description, then locks the door after Sandra has left. Nick escorts Foster to the store's back room to show him his Nazi memorabilia. Disturbed, Foster attempts to leave, but Nick holds him hostage with a gun. After Nick destroys the snow globe, Foster stabs him with the stolen switchblade, then shoots him. At the station, Prendergast explains to Yardley that his suspect is dangerous, but Yardley disregards him. In his office, Prendergast admits to Sandra that he made the choice to retire for his wife’s emotional well-being. Sandra encourages Prendergast to pursue his suspect, despite Yardley, and the two head out together to investigate. From the army surplus store, Foster calls Beth again and threatens that he is “past the point of no return.” Arriving outside Mr. Lee's convenience store, Prendergast notices a billboard he was staring at earlier during the traffic jam. Prendergast climbs a hill to view the highway where Foster’s abandoned car still sits, and he notes the license plate, which simply reads "D-FENS." Now dressed in dark clothes from the army surplus store, Foster walks into another construction site and uses a rocket launcher from Nick's shop to detonate construction machinery. Prendergast and Sandra identify Foster from the license plate and visit his mother's residence. She is despondent, but Prendergast speaks to her gently and discovers that Foster lives there and works for a weapons manufacturer. Nearing Venice, Foster crosses a private golf course and threatens two elderly players with a gun. He then hops over a private fence and discovers a groundskeeper’s family secretly using a swimming pool. While hiding from police sirens, he wields a gun and explains to the frightened family that he lost his job because he was “not economically viable.” After the police leave Beth’s house, unable to help her, Foster calls from a payphone around the corner. She realizes he is nearby and runs out her back door with Adele. After Sandra discovers that Foster lost his job over a month ago, Prendergast surmises from the map that he is headed toward his ex-wife’s house. At Beth’s house, Foster watches old home movies and plays with Adele's water pistol. When his wife phones at the station yet again, Prendergast finally stands up to her nagging. Lydecker and the other officers surprise Prendergast with cake and a stripper, but Prendergast and Sandra are on their way out. The newly empowered Prendergast hears Lydecker make an insulting remark about his wife, and he punches Lydecker in the face. As Prendergast and Sandra arrive at Beth's house, Foster is about to leave for the pier, in search of Beth and Adele. Sandra leads the way, but Prendergast stalls when he realizes he is missing his police pistol. A gunshot rings out, and Prendergast finds Sandra shot in the stomach in the backyard. Sandra gives Prendergast her weapon, and he chases Foster. At the end of the pier, Foster corners Beth and Adele. Prendergast engages Foster in conversation, allowing Beth to grab Foster’s gun and run to safety. As Prendergast holds him at gunpoint, Foster threatens that he has another weapon. Just as he pulls the weapon from his vest, Prendergast shoots. Mortally wounded, Foster reveals he is holding Adele's water pistol. He falls from the pier into the ocean. After Sandra is taken to the hospital, Prendergast sits on Beth’s porch with Adele and hints that he will not retire after all.