Much to the despair of her husband John, wealthy New York socialite Margaret Morgan hires former criminals to be her house servants. When she goes to court because her daughter Brenda has been arrested for reckless driving, Margaret is moved to hire Muggs, leader of the East Side Kids gang, who has been arrested for vagrancy and being a public nuisance, after the judge insists that he get a legitimate job. Now a chauffeur, Muggs brings the whole gang with him and puts them to work polishing cars. Muggs is instructed on proper etiquette, and when an engagement party is held for Brenda and her conservative fiancé Virgil, Muggs and the gang serve the food. At the end of the evening, one of the guests discovers that her diamond necklace is missing, and John accuses the East Side Kids of the theft. However, everyone recalls seeing a stranger at the party, whom the Morgans' regular maid Maisie now remembers as someone she met at Danceland, a dance hall on the lower East Side. Muggs convinces John not to call the police until he and the boys have had a chance to investigate. Maisie goes downtown to Danceland with Brenda, who dresses up like a gangster's moll in order to fit in. They meet with gangster Dips Nolan and learn that he plotted the jewelry heist with Diamonds, who was the stranger at the party. Nolan becomes suspicious when naïve Virgil, who has followed Brenda to the dance hall, uses her real name and asks him to throw a fake fight so that he can prove his manhood. Nolan instead knocks Virgil out and kidnaps Brenda. Muggs and Glimpy, meanwhile, see Diamonds leave for the dance hall and search his apartment. Although they find nothing, Diamonds and Nolan return with Brenda, and the entire East Side Kids gang captures the criminals and retrieves the diamonds. Later, Brenda is pleased to find that Virgil's East Side adventure has transformed him into a more confident and adventurous person.