Heir to a Balkan throne, Prince Nicholai falls in love with an American vocalist who is touring with an operetta company in Europe. When he makes known his intention to renounce his heritage and marry Mary Lou, his mother has him locked up and orders Mary Lou back to the United States.

Cameo Kirby, an honest riverboat gambler who works the Mississippi, rescues a girl from a gang of ruffians in New Orleans, but she disappears after he sings her a love song.