A schoolteacher gets a secretarial job at a gangster-run nightclub.

When virtuous schoolteacher Anne Leeds, a recent Smith College graduate, answers a classified ad for a part-time secretarial job during the night shift at the Tonic nightclub, crude but likeable Rocco, a co-owner of the club, is charmed by Anne's flawless English and innocence about his trade. After hiring Anne, Rocco's younger partner, playboy Tony Armotti, angrily complains that Anne's background does not fit the club's profile. Anne's first night includes witnessing an alleyway brawl and decoding a bookie's message about one of Rocco's bets. Before the club opens, Rocco proudly introduces Anne to the staff including headwaiter Eduordo, band leader Ray Anthony, bartender Mike and busboy Hussein Mohammed. Later that night, while Ray and his orchestra are playing to a crowded house, regular Stowe Devlin, a college graduate like Anne, offers to befriend her, but Anne claims that they are both "tourists" in the rough crowd and she prefers learning from the staff. When a customer's wife calls in search of her adulterous husband, the customer demands that Tony fire Anne after she inadvertently tells his wife that he is at the club. Tony gladly acquiesces to the belligerent man's demand, but when Rocco insists that Tony hire Anne back, he agrees to visit her at the school where she teaches the following day. Once inside her classroom, Tony reluctantly offers Anne the job, but Anne suggests that her self-confidence makes Tony uncomfortable. When Ann gives one of her young pupils money for lunch, Tony remarks that she is naive to be deceived by the student's ruse. Anne defends her decision to trust people and accepts his job offer. Back at the club, after Rocco, Tony and the club's torch singer Ivy Corlane jokingly propose a wager regarding Anne's sexual experience, Ivy ascertains from Anne that the secretary has "no hits, no runs, no errors." Later that night, dancer Patsy St. Clair tells Anne that she aspires to be a cook and compete in a cooking contest for a new stove, despite her mother Crystal's insistence that she concentrate on marrying. When Patsy reveals that she has had no time to create a recipe, Anne offers her a family carrot cake recipe. Meanwhile, a bloody Hussein returns to the club complaining that he must change his name to avoid being beaten up because of his ethnic background. When Hussein explains that his father has agreed to the change providing the teenager pass his algebra class, Ann offers to help him with his lessons. After a night of deftly handling almost all the staff's needs, Anne learns from Hussein that the young women filing up and down the staircase outside the club are going to Tony's apartment. Days later, when Anne is late for work, Rocco reveals his venerable and fatherly side to her when he asks her to be on time to keep him from worrying. Hussein has received a difficult algebra test to finish by the following morning and when Anne offers to find a customer to help him with the test, Tony insinuates that the job requires a more enticing woman and sends Ivy. Meanwhile, Patsy returns from the contest just in time for her number, a newsgirl strip routine in which she reveals, under several layers, a first place cooking contest ribbon. Back in the office, Rocco confides in Anne that bitterness about his past marriage made him pressure young Tony to stay away from decent women. Throughout the night, Tony hushes staff and customers alike when they show signs of disreputable behavior in front of Anne. When Anne finds out later that Tony has told the staff Anne is a "greenhorn," under the guise of protecting her, she runs to his apartment to demand an explanation. Tony claims that maintaining her virtue is his responsibility, but Anne retorts that she is not naive, just inexperienced. After sharing a few drinks, Tony brusquely challenges her to "handle" his pass and kisses her. To his surprise, Anne eagerly returns the kiss. When Rocco calls to report that Anne's landlord, Mr. Shea, is worried that Anne has not returned home, Tony lies to Rocco that Anne is staying with Crystal and Patsy. After a drunken Anne then insists on spending the night and professes her love, Tony hurriedly drives her to Patsy and Crystal's apartment. Rocco, who spotted the couple as they left and assumed Tony took advantage of Anne, punches his friend when Tony returns to the apartment. The next morning, Anne tells Rocco that nothing happened between her and Tony and admits that she loves him, despite Rocco's advice that Tony is a "bad character." Later, Rocco returns to the club and apologizes to Tony. When Tony insists that Anne leave the club, Rocco announces that she has already quit, causing Tony to become strangely sullen. Days later at school, Tony walks into Anne's classroom in midst of a fight between Anne and her students and tenderly orders them to apologize to their teacher. Although softened by Tony's good behavior, Anne refuses his offer of severance pay and his suggestion that she return to New England. Back at the club, Tony's tolerance is tested as each staff member eagerly asks him why Anne quit. He then discovers from Rocco that Anne is now working for Waxie London, an ex-convict who runs a club that fronts a gambling racket. Later that night at Waxie's, Tony is ordering Anne to quit her job when the police raid the club. After helping Anne out a back window, Tony begs her to return to the Tonic. Anne vehemently rejects his offer and flees, but several nights later, Anne is back working at the Tonic, where the staff celebrates her return as Rocco and Tony offer a champagne toast at the bar.