Karl, a German diplomat in Paris, discovers that his fiancee, Diane, has been cheating on him. He tells her that he would rather marry a "girl of the streets" than her. Outraged, Diane decides to grant hi his wish, and enlists the services of a Spanish singer/dancer from a disreputable nightclub to pose as a sophisticated, convent-educated singer, and surreptitiously arranges for her to meet Karl.

Karl von Arnim, military attaché with the Prussian legation at Paris, breaks his engagement to the beautiful French Countess Diane des Granges because she is unfaithful and in a fit of anger declares that he would rather marry a woman of the streets. Enraged, Diane conspires with Baron Finot, Napoleon III's chamberlain, to arrange for Karl to meet Nanon del Rayon, a singer at "The Smoking Dog" cabaret, in the guise of a real lady (La Paiva). The ruse is a success, and Karl and Nanon marry. Diane holds a wedding banquet for the newlyweds at "The Smoking Dog," where she reveals Nanon's real identity. Nanon flees, then returns to sing at the cabaret, where Karl comes to take her away.