Joan Mitchell, the child star of the Kippy Korn Flakes radio program "Underworld Angel," is dissatisfied with the quality of her scripts. When Joan complains to J. C. Crandall, the head of the company, that her gangster dialogue is not realistic, Crandall promises to speak to the show's writers. Bill Morgan, Kippy Korn's press agent and the fiancé of Joan's guardian, Aunt Pat, suggests staging Joan's disappearance as a publicity stunt to stimulate listener interest, but Crandall forbids any use of sensationalism. That night, after Bill presents Joan with another unrealistic script, she decides to write her own, and is advised by her butler, Higgins, to study her characters thoroughly. Joan's opportunity to research the underworld presents itself when Pinky, a safecracker, breaks into the Mitchell house. Joan pretends to be a juvenile cracksman and helps him to open the safe. Thinking that Joan is a homeless waif, Pinky takes her to the apartment he shares with fellow gang members Stogey and Jitters. After Joan makes up a fictitious story that her "father," Joe Foster, is in jail, the three christen her "Small Change" and welcome her into their gang. The next morning, Pat discovers that Joan is missing and assumes that she has been kidnapped. Although news of her abduction is splashed across the headlines, Pinky, Stogey and Jitters are unaware that their "Small Change" is the missing radio star. When Crandall accuses Bill of staging the kidnapping as a publicity stunt, the police become suspicious. After Joan phones home and the police overhear Bill talking to her, Lieutenant Hackett arrests him for questioning, but he escapes. Meanwhile, Joan convinces her friends to burglarize a house that night, but when the alarm sounds and brings the police, the four narrowly escape. Later, Pinky convinces his friends that they should reform for the sake of "Small Change." Deciding to reunite her with her jailbird father, they locate a man named Foster in a mid-town jail. While Jitters and Stogey go to post Foster's bail, Pinky takes Joan to buy a new dress. Joan is standing on the sidewalk in front of the store when Bill sees her and tries to take her home with him, but Pinky then slugs Bill and flees with Joan. The commotion brings the police, and Bill is arrested once again. In order to win his release and locate Joan, Bill admits to concocting Joan's kidnapping. Hackett then frees Bill, giving him two hours to return with Joan. Meanwhile, at the mid-town police station, Stogey and Jitters post Foster's bail, and when they tell him about his "daughter," he plays along with the story and returns to the apartment with them. There, Joan tells Foster who she really is and proposes that she leave with him to spare her friends' feelings. Realizing that Joan is the missing radio star, Foster promises to take her home, but after they leave the apartment, he kidnaps her and takes her prisoner aboard the S. S. Lady Luck . Bill, meanwhile, is searching the neighborhood for Joan and when he questions Louie, the proprietor of a pool hall who knows the gang, Louie realizes that Foster is not Joan's father and that she is in trouble. Louie then phones Pinky and tells him that Foster is in league with the owner of the ship called the Lady Luck . Pinky and the gang join Bill at the pool hall, and they all drive to the ship. After a battle with Foster and his gang, Joan and her friends subdue the criminals, and the police, drawn by the gunshots, arrive and arrest the gang. When the Judge suspends the sentences of Pinky, Stogey and Jitters and places them in Joan's custody, the three become supporting players in her new radio show.