Sally Murphy helps her mother run a boarding house for police rookies that includes Tommy Bradley and Jane's brother Jimmy. The latter is in love with Sue Duffy, daughter of police Captain Duffy, but Jimmy can't get along with Sue's father. Jimmy plans secretly to join the notorious gang led by Ed Boyd. Tommy's kid brother, Billy, arrives for a visit all shiny and spiffy in his military cadet uniform, and Sally falls for him at once. Tommy is taking the pair to the ice cream shop and, while walking a discreet distance behind the two young lovebirds, glances up an alley and sees Boyd's gang, including Jimmy, robbing a fur shop. Tommy is shot down and the gang escapes. Jimmy severs all connection with the police and becomes the manager of Boyd's night club. Jane is determined to find out who killed Tommy even if it implicates her brother, whom she suspects after finding a clue in his room. She takes Billy to the night club and puts on a song and dance while Billy searches for evidence, which he finds. After putting Captain Duffy and his rookies on the trail of the fur shop loot, Jane and Billy discover that Jimmy had joined the gang under Captain Duffy's order. Boyd has also learned the same and decides to have Jimmy killed.