A woman encounters a robber in her home, and he hits her and steals her pearls. Later at a dance hall, Preen Lazetti dances with taxi dancer Katy Dolan until his girl friend Dora Cobb, gets angry. When police sergeant Dan McKennan sees his son Dave, also a policeman, dancing with Katy, he becomes morally outraged and sends Dave home. Preen knows Dan is after him for the robbery and gives the pearls to Dora. Dora slips the pearls into Katy's purse in the ladies' room, and when Dan searches them, he finds the pearls and arrests Katy. When he returns home, he reprimands Dave for going into a dance hall, and when Dave rebels, they put on their boxing gloves and fight until Dan knocks Dave out, proving his superiority. Although she is innocent, Katy accepts the blame for the robbery and serves six months in the women's reformatory. When she is released, she returns to the dance hall as it is the only means of work she is able to get. Preen pretends not to know what happened the night of her arrest, and tells her that he has a new racket and wants her in on it with him, as Dora is now out of the picture. After a taxi driver is robbed and murdered, Katy is brought in for a police line-up. When she is released, she runs into Dave, who treats her to lunch and believes that she was framed. Although she is initially distrustful of him, he shows her kindness and gets her work at the coffee shop where they are eating. Dave makes a date with Katy, and she confesses that she originally had plans to revenge herself upon Dan, whom she believed framed her, but has fallen in love with Dave and forgotten her plans. At home, Dave has a confrontation with Dan and bitterly moves out of their apartment. He also leaves the force, only to discover that Katy has been fired by the luncheonette after his father told them of Katy's past. Despite Dave's marriage proposal and her sincere love for him, Katy leaves him , fearful he will find fault with her some day. In the meantime, with the taxi driver killer still at large, Dan fears for his job. Katy returns to the dance hall where she pretends to love Preen, and induces him to confess to the murder. She promises to wait for him while he gets the payoff. After Preen leaves the dance hall, he shoots Dora in the back of a cab because she knows too much. Katy calls Dave and warns him about Preen, but Dan finds her and threatens to put her on a train for the West coast. She convinces him of Preen's guilt and warns him that Dave is going after Preen alone. Dan calls out the rest of the force, and when they find Dora dying in the cab, she confesses that she framed Katy, which gives Dan new faith in Katy. Dave forces his way into the payoff room, and after some gunfire, he emerges with Preen in his custody. Dan returns his badge to Dave, as he had never turned it in, and takes Preen to the station. Reunited, Katy and Dave return to Dan's apartment, where they prepare dinner for Dan.