Walter Burns (Cary Grant) is a hard-boiled editor for The Morning Post who learns his ex-wife and former star reporter, Hildegard "Hildy" Johnson (Rosalind Russell),[a] is about to marry bland insurance man Bruce Baldwin (Ralph Bellamy) and settle down to a quiet life as a wife and mother in Albany, New York. Walter determines to sabotage these plans, enticing the reluctant Hildy to cover one last story, the upcoming execution of Earl Williams (John Qualen) a shy bookkeeper convicted of murdering an African-American policeman. Walter insists Hildy and her fiancé Bruce join him for lunch. At the restaurant, Hildy insists that she and Bruce will be leaving in two hours to take a night train to Albany to be married the following day. Walter attempts to convince Bruce that Hildy is the only one who can write a story to save wrongly convicted Earl Williams. After several attempts through deceit and lies to convince Hildy to stay, Hildy eventually agrees on the condition that Walter buys a $100,000 life insurance policy from Bruce in order to receive the $1,000 commission. In the meantime, Hildy bribes the jail warden to let her interview Earl Williams in jail. Williams explains that he shot the police officer on accident. Hildy uses economic theory to explain the murder of the cop to Williams, insisting that he shot the gun because of production for use.
Walter does everything he can to keep Hildy from leaving, first setting up and accusing Bruce of stealing a watch, forcing Hildy to bail him out of jail. Exasperated, Hildy announces her retirement from her profession; however, when Williams escapes from the bumbling sheriff (Gene Lockhart) and practically falls into Hildy's lap, the lure of a big scoop proves too much for her. Walter frames Bruce again, and he is immediately sent back to jail. At this point, she realizes that Walter is behind the shenanigans, yet is powerless to bail him out again. Williams comes to the press room holding a gun to Hildy and accidentally shoots a pigeon in fear. Hildy takes the gun from him. Bruce calls, and she tells him to wait, because she has Earl Williams in the press room. Williams's friend Mollie comes looking for him, assuring him that she knows he is innocent. When reporters knock at the door, she hides Williams in a roll-top desk. At this time, the building is surrounded by other reporters and cops looking for Williams. Hildy's stern mother-in-law-to-be (Alma Kruger) enters berating Hildy for the way she is treating Bruce. Upon being harassed for Williams's whereabouts by the reporters, Mollie jumps out of the window, but isn't killed. Annoyed, Walter has his colleague "Diamond Louie" (Abner Biberman) remove Mrs. Baldwin from the room "temporarily". Hildy wants to try to get Bruce out of jail, but Walter convinces her that she should focus on her breakthrough story.
Bruce comes into the press room having wired Albany for his bail asking about the whereabouts of his mother, as Hildy is frantically typing out her story. She is so consumed with writing the story that she hardly notices as Bruce realizes his cause is hopeless and leaves to return to Albany on the 9 o'clock train. "Diamond Louie" enters the room with torn clothes, revealing that he had hit a police car while driving away with Mrs. Baldwin. Louie reveals that he wasn't sure whether or not she was killed in the accident. The crooked mayor (Clarence Kolb) and sheriff need the publicity from the execution to keep their jobs in an upcoming election, so when a messenger (Billy Gilbert) brings them a reprieve from the governor, they try to bribe the man to go away and return later, when it will be too late. Walter and Hildy find out in time to save Williams from the gallows and they use the information to blackmail the mayor and sheriff into dropping Walter's arrest for kidnapping Mrs. Baldwin. Hildy receives one last call from Bruce, again in jail because of having counterfeit money that was unknowingly transferred to him by Hildy from Walter. Hildy breaks down and admits to Walter that she was afraid that Walter was going to let her marry Bruce without a fight. Walter and Hildy send money to bail Bruce out of jail.
Afterward, Walter tells Hildy they're going to remarry, and promises to take her on the honeymoon they never had in Niagara Falls. But then Walter learns that there is a newsworthy strike in Albany, which is on the way to Niagara Falls by train. Hildy agrees to honeymoon in Albany, accepting that Walter will never change. Walter leads Hildy out of the press room, asking her to carry her own suitcase.