Hunted by the police, thieving Mary Flynn, takes shelter in the car of John Reagan to break loose from her underworld associates. John gives Mary a fresh start in life, and his son, Tim, an assistant district attorney, soon falls in love with her. A jewel collector named Forbes, who knows that the elder Reagan's past was a little shady, blackmails him into stealing a valuable diamond. In order to protect her mentor, Mary steals the jewel. Piccadilly Charlie, Mary's old accomplice, wants the stone also and kills Forbes in an attempt to get it. John is found with the body and is arrested for the murder. Mary sets a trap for Charlie, using the diamond as bait. Charlie returns for the stone, and Mary captures him, handing him over to the police. John is released from jail, and Tim and Mary are wed.