Chicago's ace reporter Hildy Johnson (Pat O'Brien) wants to quit newspaper work and get married, but his editor, the ruthless and egomaniac Walter Burns (Adolphe Menjou), is determined to keep him on the job. Hildy refuses to talk to Walter, knowing his persuasive powers, so Walter sets off a fire alarm outside the apartment of Hildy's fiancee, Peggy Grant (Mary Brien). Unable to resist, Hildy runs to the street, after which Walter corners him and takes him out for drinks.While the two men drink, Walter reminisces about the great stories that Hildy covered and paints a boring picture of married life. Hildy manages to escape, and drops in on the press room at the courthouse, where the reporters are waiting for the hanging of Earl Williams (George E. Stone), who killed a black policeman. The reporters want Williams hanged at five in the morning, so they can make the morning edition with their stories. The politicians, on the other hand, want him hanged just before the election, so they can count on a large black vote.Hildy learns that a new psychiatrist has been called in to examine Williams. During the examination, Williams escapes. After the other reporters run from the room to investigate, Hildy bribes someone to tell him the story of Williams' escape using the money Peggy gave him for their trip to New York.Peggy follows Hildy to the press room, complaining that he always puts the paper ahead of her. In the midst of the manhunt, the governor's reprieve arrives, but no one sees the messenger except the sheriff and the mayor. They send the man away, asking him to come back after the hanging.While Hildy is alone again in the press room, Williams climbs in through a window. Hildy hides him in a roll top desk. Molly Malloy (Mae Clarke), a prostitute who helped Williams after he shot the policeman, sees Williams' hiding place, and when the other reporters are about to discover him, she jumps out the window to distract them, killing herself. In the confusion, Walter arrives. He is delighted with Hildy's work, flattering him with the notion that he has brought down a government. Furious at being kept waiting, Peggy breaks off her engagement. The reporters find Williams in the desk, and the sheriff arrests Hildy and Walter, but just then, the man with the reprieve returns, to Walter's delight. Williams walks away a free man.Peggy returns and Hildy quits his job and proposes to her again. Walter gets sentimental, and realizing that Hildy really doesn't want to leave the newspaper business, Peggy says she will stay in Chicago. Hildy insists on leaving and Walter gives him a pocket watch as a going-away present. As soon as Peggy and Hildy leave the room, however, Walter (evil and devious to the end) phones the police at the train's first stop, asking them to arrest Hildy, who he claims has stolen his watch.