Lorenzino de 'Medici manipulates Alessandro ruler of Florence to save his beloved Bianca.

Martha Eggerth heads the cast of Casta Diva, but the central character is famed Italian composer Vincenzo Bellini, here played by American actor Phillips Holmes. Paying but scant attention the facts, the film concentrates on Bellini's colorful love life. Evidently the film went through several rewriting processes, as witness the curious performances of Donald Calthrop and Arthur Margetson, whose characters do complete about-faces halfway through the story. Amidst so many British accents, Martha Eggerth's Polish intonations seem out of place, but she photographs beautifully and sings quite well. Casta Diva was attractively filmed on location in Naples. Not to be confused with the 1954 remake (by Gallone himself) or to the English language version "The Divine Spark" (also directed by Gallone and starred by Eggerth).

The diary of a missing singer is published by a girl with an extraordinary voice that sounds very much like hers.