While in New York seeking work, Cynthia, a young English girl, meets Bruce Crittenden and George Rhode who introduce her to Madame Savarin, a wealthy woman seeking a companion for a sea voyage. She hires Cynthia, and while at sea, Cynthia discovers that Bruce is the ship's purser. Cynthia's father was a famous wireless expert who taught her how to read code, which enables her to overhear a plot to sink the ship and steal Mrs. Savarin's jewels. Soon after, the crew mutinies, and while Rhode and Bruce fight the crew, Cynthia sounds the alarm. As he is attempting to foil the jewel thieves, Bruce falls overboard, and Cynthia swims to his rescue with the jewels strapped to her back. They are rescued by a government patrol boat and taken back to New York where Cynthia and Bruce are married.
