A district attorney's arrogance almost costs him his career.

When prostitute June Perry is arrested for tapping on the window of gangster Valentine "Vanny" Powers in a solicitous manner, Powers' attorney, Tom Cardigan, defends her in court. By convincing the jury and the female judge that June's tapping could have been the tapping of an innocent mother or wife, Tom secures an acquittal for his attractive client and later takes her to his bachelor "hideout" apartment. Because of her past, June becomes Tom's mistress but, like a wife, worries about his excessive drinking and his criminal associations. After Powers is shot and wounded by his rival, "Birdlegs" Duffy, Tom is asked by Powers to take a job as the district attorney's first assistant, but Tom refuses, stating that if he ever became a prosecutor, he would be an honest one. Lured by the prospect of the governorship, however, Tom eventually joins the district attorney and soon takes over his job. As promised, Tom becomes a rigorous prosecutor, forcing confessions out of killers with the same dramatic flair he used to defend Powers and his gang. Although still in love with June, Tom is tempted by the adoring Lillian Ulrich, whose father is a powerful political boss, and during a drunken night out with her, marries her. That same night, Tom breaks the news to June, who is devastated but understanding. Tom, however, quickly realizes that he has made a mistake with Lillian and arranges for an annulment. Soon after, Powers murders Duffy in front of June, and June is arrested as a material witness. During Powers' trial, Tom questions June, who out of fear for Tom's life, has refused to name Powers, and eventually forces an identification out of her. As part of his summation, Tom then reveals to the court that he and Powers had served time together in a reform school on a burglary charge. After declaring himself a phony, Tom renounces his ambitions and reunites with June.