On an August 1972 afternoon in Brooklyn, New York, three young men, Sonny, Sal and Stevie, enter the First Brooklyn Savings Bank near closing time. Inside, Sal sits at the desk of manager Mr. Mulvaney and pulls out a machine gun from his briefcase. After a panicked Stevie leaves, Sonny takes a rifle from a flower box and warns Mulvaney and the tellers that he will shoot anyone who triggers an alarm. Sonny then closes the window drapes and spray paints over the lenses of the security cameras then orders Mulvaney to open the vault. Cautioning Mulvaney and the others that he knows all of the security measures as he has worked at a bank, Sonny sends a teller, Miriam, with Mulvaney into the vault to fill plastic bags with money. Although she complies, Miriam begins crying and admits there is only a little over a thousand dollars in the vault as the rest of the money had been picked up earlier that day. Dismayed, Sonny instructs head teller, Sylvia, to empty the tills, reminding her that he knows that one slot of each drawer is rigged to set off a silent alarm. While allowing Mulvaney to answer the ringing telephone, Sonny rejects a pile of marked money and when, in mounting agitation, he swears, Sylvia asks him to watch his language. After setting fire to the bank register, Sonny demands the building keys from the elderly guard, Howard, who is paralyzed with fear. Meanwhile, Sal notices a man across the street staring intently at the bank and the robbers realize the smoke from the burning register is visible. When Howard remains too terrified to act, Mulvaney calmly unlocks the door and reassures the business neighbor that a cigarette caused the smoke. Sonny then orders Mulvaney and the tellers into the vault, but one woman insists they will suffocate and Sylvia pleads to use the bathroom. Exasperated, Sonny inspects the restroom where he surprises teller Maria Sandora who has been changing clothes and is completely unaware of the hold-up. While Mulvaney answers another phone call, Sonny herds the tellers into the vault, then is startled when Mulvaney informs him the call is for him. On the phone, Sonny is addressed by Detective Sgt. Moretti who is in the barber shop across the street. As Sonny and Sal watch in disbelief, the bank is surrounded by wailing police cars and a growing crowd of curious onlookers. Sonny hangs up on Moretti and asks Mulvaney why he reported the robbery when no one had been hurt. The phone rings and Sonny barks a threat into the receiver only to discover the call is for Jenny, another teller, from her husband. When Moretti telephones again, Sonny informs him that he and Sal are Vietnam veterans and know how to kill. Despite Sonny’s subsequent assurances to the hostages that they will be fine if they obey, Howard suddenly collapses and Sylvia explains that the older man has severe asthma. Incredulous that a bank would hire an infirm guard, Sonny leaves Howard to the tellers’ ministrations while he and Mulvaney block off the bank’s back entrance with a large piece of furniture. Outside, FBI agent Sheldon arrives and is displeased by the large number of police whom Moretti admits he hoped would scare the robbers into surrendering. Sheldon watches silently as Moretti waves away reporters while, overhead, television crews in helicopters photograph the mob of police and spectators. As Sonny frets about his next step, Moretti telephones and encourages him to let one hostage go as a sign of good will. Deciding to release the ailing Howard, Sonny and Sylvia help the elderly man through the front door, but the guard is terrified when numerous police leap forward with guns drawn, unsure if he is a hostage or criminal. Alarmed, Moretti, bids the anxious policemen to holster their weapons, then, demonstrating that he is unarmed, pleads with Sonny to come out to the street to see the hopelessness of his situation. Reminding Moretti that Sal is inside holding a gun on the remaining hostages, Sonny, carrying a white handkerchief, steps outside and observes that the forces surrounding the bank resemble a militia. When Moretti presses Sonny to surrender, suggesting that he will only be charged with robbery, Sonny angrily tells the detective that he knows that armed robbery is a federal offense. Demanding someone “better” with whom to negotiate, Sonny turns to the crowd and begins yelling “Attica,” referring to the recent New York prison riot and hostage situation brutally squelched by police that resulted in the death of inmates and hostages alike. Excited by the exhibition, the crowd chants along and cheers Sonny, infuriating Moretti. As Sonny returns to the bank, Sylvia, who has remained in the doorway to speak with a reporter on a fire escape nearby, refuses Moretti’s attempt to pull her outside, explaining that she is obliged to return to her fellow tellers. Back in the bank as Sylvia excitedly relates her interview with the reporter, Sonny takes a call from a television reporter. Turning on Mulvaney’s small TV set, Sonny sees himself photographed through the bank’s glass doors. Admitting that he is committing the robbery because he cannot support his wife and two children, Sonny then grows angry with the reporter and swears, prompting the live broadcast to abruptly cut off. Sonny then tells Sal privately that he believes the police will make a deal with them because of the excessive publicity, but Sal disagrees and reminds him that they vowed to make a clean getaway or commit suicide. A little later, Sonny is taken aback when an anonymous caller urges him to kill everyone. After reflecting on their situation, Sonny tells Sal they can demand a helicopter to take them to an airport where they can flee the country, but Sal remains unconvinced. Insisting that holding the hostages gives them bargaining power, Sonny encourages Sal to choose any country in the world to go and Sal suggests Wyoming. Returning outside to present their demands to Moretti, Sonny playfully stirs up the crowd again, but is abruptly tackled by a man who beats him. After the police pull the man away, Moretti tells the stunned Sonny that the man is the boyfriend of one of the hostages. Although shaken, Sonny requests a helicopter and jet plane and also asks to see his wife. Back inside the bank, the air grows stuffy after Moretti orders the air conditioning disabled. Going to the back of the building in an effort to restart the cool air, Sonny sees the figures of numerous police through a small window and, panicked, shoots his rifle at the window, terrifying the tellers. The shot results in mayhem outside and Moretti anxiously calls to Sonny on a bullhorn demanding to know why he fired. Drained and anxious, Sonny goes outside where the eager onlookers have begun mimicking Moretti calling for Sonny. Moretti informs Sonny that he cannot bring a helicopter into the narrow street, but has arranged for a bus or limousine. Sonny asks for pizza and aspirin for the tense hostages, then later pays the delighted delivery boy with hundreds of the marked bills, before flinging more bills to the excited crowd. As the stifling afternoon drags on, the tellers pass the time chatting quietly and Sonny shows one woman how to perform a military rifle drill. When Sylvia smokes a cigarette out of nervous anxiety, Sal expresses his disgust with smoking, claiming that the body is “a temple.” Amazed, Sylvia mocks him for being a “temple” while robbing a bank, but Sal dismisses her as “weak.” Later, a disheveled young man in a hospital robe, Leon Shermer, steps out of a police car and a stunned Moretti telephones Sonny to inform him that his wife has arrived. Overwhelmed by the police and gaping crowds, Leon faints as word spreads through the police ranks that Sonny is a “fag.” After Leon revives in the barber shop, he tells Moretti of his difficult relationship with Sonny, which included a church wedding. Leon reveals that upon learning from a psychiatrist that Leon is a woman in a man’s body, Sonny has been obsessed with providing him the money to get a sex-change operation. Admitting that stress has provoked him to attempt suicide, Leon dismisses Moretti’s intimation that he could be held as an accessory to the robbery, then breaks into tears and refuses to speak to Sonny. Reporters quickly confirm Leon’s story and, in the bank, Sal grows alarmed when a television newsman describes the robbery as conducted by two homosexuals and urges Sonny to correct the error. At dusk, the lights inside the bank are turned off and when Sonny goes outside responding to Moretti’s summons, he finds himself facing Sheldon. The federal agent informs Sonny that he has taken over and will put an end to the circus atmosphere, then insists on going into the bank to verify the condition of the hostages. Inside, Sheldon notes Sal’s grim demeanor and assures the hostages that their freedom is imminent. Upon departing, Sheldon assures Sonny that they will “take care” of Sal, but Sonny furiously counters that he will never sell out his friend. Moments later, Mulvaney unexpectedly collapses and Sylvia reveals that he is a diabetic. An ambulance physician is sent into the bank to tend to him while Sheldon then informs Sonny that Leon will now speak with him on the phone. After an awkward conversation and despite Sonny’s declarations, Leon evades any personal promises, pleading with Sonny to confirm that he had no knowledge of the heist. Afterward, Sonny asks Sheldon to speak to his other wife, Angie, and their two children. When Angie is put through on the phone, however, she proves so distraught that she will not listen to Sonny, who hangs up in frustration. When Sonny suggests that the recovering Mulvaney depart with the doctor, the manager curses him and tells him not to pretend that he is a good person. Disturbed when his mother arrives and beseeches him to surrender, Sonny instead dictates his last will and testament to Sylvia, leaving insurance money for Leon to have his operation. When a limousine arrives, Sonny inspects the vehicle carefully and refuses Sheldon’s appointing another agent as driver, choosing instead the easy-going African American who delivered the car. When Sheldon agrees too readily, however, Sonny surmises correctly that the delivery driver is a police plant and accepts the agent. Gathering the hostages around them for cover, Sonny and Sal shuffle to the car and enter safely and, amid hoots and jeers from the crowd, depart for the airport. Once at the airport on the tarmac, Sheldon points out their jet to Sonny and asks for another hostage release. Sonny tells Sylvia to go, but she has a younger, volatile teller leave instead. At a secret verbal cue from Sheldon, who is standing by the passenger window, the driver secretly pulls a pistol and asks Sal to point his gun upwards so it will not discharge by accident while the others exit the car. As Sal complies, Sheldon reaches into the car and grabs Sonny’s rifle barrel as the driver turns and, firing between two hostages, shoots Sal in the head. The shocked hostages are quickly taken from the car as a stunned Sonny is handcuffed and placed under arrest.