Ernesto and Marius are two struggling musicians in Milan. Rosa, their landlady’s daughter, worships Ernesto, who returns her affection in a casual way. Ernesto secures an engagement in America, and Rosa pleads to go with him, but he will not hear of it. Two years later, Mario tries his fortune in America. Ernesto, now a popular tenor, cuts Mario dead when they meet. Ernesto is in love with Yvette. a soprano in the same opera company, but she takes, his love lightly. Doubting the wonders of her own voice, Yvette sings in the streets of the Ghetto where Mario recognizes the unusual qualities of her voice, secures her permission to try it out and she is bailed as a wonder. Discovering where Ernesto is playing, Rosa waits for him at the stage door. Ernesto scornfully refuses to recognize Rosa and she swears to be revenged. Mario and Yvette fall in love with each other. Later he discovers her real identity, and angrily goes to her home. He arrives in time to save her from the forced embraces of Ernesto, for which she is grateful and gains recognition for Mario by singing his composition, “The Song of the Ghetto.” In the midst of their success, Rosa attempts to stab Ernesto, but instead strikes Mario when he rushes between them. The wound fortunately proves slight. Ernesto and Rosa beg his forgiveness, which is granted, and Yvette acknowledges her love tor Mario, as he entwines her in his arms.