When Marcel, a waif, saves master crook Burke from the police, Burke adopts the youngster and teaches him his profession. Years later, Marcel has become a master crook himself, working under the name of Michael Lanyard. His clever work baffles the Paris police, who dub him "The Lone Wolf". The Pack, a gang of criminals, notifies The Wolf that unless he joins them, he is marked for destruction. Lucy, an undercover agent masquerading as a crook to expose the gang, helps The Wolf escape. This inaugurates a series of adventures in which Lucy and The Wolf are pursued by the gang, finally making their escape to England by plane. The Pack follows, only to meet their death in a plane crash. Liberated from his tormentors, The Wolf vows to go straight and marries Lucy.

English hellraiser Richard Farrington is sent by his wealthy titled parents for a visit to his aunt and uncle in Long Island, New York. On the ocean voyage, Richard meets Betty Winthrop, the ward of the wealthy Van Allen family. Introducing himself he mistakenly gives her the card of John Smithers, a conman who cheated him at cards in London. He follows Betty to the Van Allen estate, where he hears her declare that she would rather marry an American criminal than a weakling English aristocrat. Determined to win her over, he pretends to be Smithers, but things don't turn out exactly the way he planned.