A killer holds the customers at a bar hostage.

At the Oasis Bar in Terminal City, newspaper reporter Harrison "Harry" D. Barnes and other patrons pay little notice to a police bulletin advising residents that a dangerous criminal is on the loose. At the same time, on a bus headed for Terminal City, Gunther Wykoff, a mentally disturbed fugitive from the State Hospital for the Criminally Insane, steals the bus driver's gun, shoots him in cold blood and flees. Intent on finding Dr. John D. Faron, the police psychologist who testified in his case, Wykoff goes to the Terminal City Criminal Courts Building and then to the doctor's apartment. Wyckoff is unable to find Faron, however, and instead goes to the Oasis Bar. There, Chuckles, the bartender, turns on the bar's new television set just as a news bulletin featuring a photograph of the escaped convict appears on the screen. Chuckles immediately recognizes Wycoff from the photograph, but when he tries to call the police, the escapee shoots and kills him. Wyckoff then holds everyone in the bar hostage, including Harry; Earl, a salesman who is there with his twenty-four-year-old companion, Helen; Skip, a waiter at the bar and an expectant father; and Freddy, an alluring barfly. After breaking a window in the bar and shooting an approaching police officer, Wyckoff calls Police Captain Henry Keiver on the telephone and demands to see Faron before nine o'clock. When Freddy tries to diffuse the volatile situation in the bar by trying to seduce Wyckoff, Wyckoff sees through her ploy and strikes her. Faron, meanwhile, has arrived on the scene and tells Keiver that Wyckoff sees him as his only friend, and that the only way to end the standoff is for him to go into the bar. The captain rejects Faron's plan as too dangerous, but the psychologist defies Keiver's orders when Wyckoff kills a police officer who had been attempting to get into the bar through an air conditioner vent. With only two minutes to go before nine o'clock, Wyckoff turns the television set in the bar back on and watches the live news coverage of his hostage stand-off. As soon as Faron enters the bar, Wyckoff says that he has come back to Terminal City to kill him. Faron, who is familiar with Wyckoff's delusions, tries to talk the fugitive out of killing while reminding him that the Army rejected him as soldier and that he a make-believe soldier fighting an imaginary war. Wyckoff becomes angry and shoots Faron, but just as he is about to turn his rage on the hostages, Freddy grabs a gun she sees behind the bar and shoots him. The wounded Wyckoff is then killed by a barrage of police gunfire as he tries to leave the bar. The hostage situation ends with a moment of joy as Skip learns that his wife has given birth.