Henry Disney, a milkman, residing in a small city, is discovered by Phipps, a lawyer, to be the heir to the title and fortune of the Duke of Walshire. Phipps and his sister, Laura, being pressed for money and anxious to maintain their social position, conspire together to arrange a marriage between the sister and the milkman before he knows that he is the Duke. Phipps has Disney assaulted and arranges to be near in order to rescue him and take him to the Phipps house. In the meantime, however, Disney has met Ethel Hamilton, one of the young social leaders of the town, and has fallen in love with her, although he doesn't dare to speak of his love on account of the great difference in their social positions. His love for Ethel, however, prevents him from falling a victim for the wiles of Laura, and he finally escapes from Phipp's house, where they are trying to keep him on the pretense that he is very ill. He then discovers that he is the Duke. The efforts of the milkman to be a Duke and to win the girl he loves lead to many humorous complications, and, finally at a ball which the milkman gives in honor of Ethel, his conduct so displeases her that she refuses his love and tells him very plainly that the social snobs who have been fawning upon him on account of his title have been making a fool of him. The milkman then begins to see a great light, and, after resenting an insult to Ethel by one of the snobs, takes occasion to tell them what he thinks of them. The dance breaks up in confusion and the milkman, sore at heart, sees that he is being used by the snobs, while they are making fun of him behind his back. He renounces his wealth and title and goes back to his milk route, where Ethel finds him. He agrees to do this on condition that Ethel will act as his instructor and teach him how to be a Duke. This she finally consents to do and he drives her home in the milk wagon, after an understanding between them which promises a happy ending to his love story.