Although Kenneth Carmont and Esther Saunders, criminal Bert Saunders' sister, love each other, Esther marries detective Elwood Collins, who agrees to stop pursuing Bert if she accepts his proposal. One night, Kenneth and Esther hide Bert, who has escaped from the police. The same night, Kenneth's father is murdered. The evidence implicates Kenneth, who cannot supply his whereabouts at the time of the crime, as that would give away Bert. Esther cannot clear Kenneth for the same reason, and because it would let her husband know that she was with her former sweetheart.

Officer Terence Shannon is the head man of the Los Angeles Flying Squadron. In this capacity, Shannon does battles with ruthless opium smugglers in LA's Chinatown

Lawrence Revel, celebrated in society circles for his success with women, is devoted to his son Dick and objects to his marrying Nellie, a cabaret dancer. To prove her unworthiness, Beau asks his son not to see her for 2 weeks. Unwittingly, Beau falls in love with the girl, but his attentions are refused.

When Judge Grant sentences Paul Rogers to jail on circumstantial evidence, Paul's sister Lena swears revenge.

Shrewd crook Boston Blackie is determined to go straight. At a celebration held on the eve of his marriage to Mary Dawson, Fred the Count plants a stolen jewel and Blackie is arrested and sentenced to twenty years in jail. Fred the Count tries to win Blackie's fiancée, but the honorable Mary rejects him. Blackie's only hope for escape is from the hospital, so he manages to get into a weakened state. He escapes from the hospital, but is trailed by the warden. Blackie refuses to shoot the defenseless man, and the warden recognizes Blackie as an honorable person and allows him to escape. Blackie frames the Count, and leaves for Honolulu with Mary

When a revolution breaks out in a small European monarchy, the king sends his crown jewels to an American banker, Maxwell Grey, to keep them out of danger. However, Madame Levine, the head of an international jewel theft ring, finds out and plans to steal the jewels. She poses as a wealthy society matron and befriends Grey. Young French refugee Diana De Lille, who at first was taken in by Madame Levine, begins to suspect that the woman is not who she says she is, and confides her suspicions to Kenneth Grey, the banker's son, who has fallen in love with her.