La Castiglione is set in 19th-century Italy during the reign of Emperor Napoleon III. The only way for Italy to declare her independence from Napoleon is to form a united front -- a monumental task, in that the various provinces aren't all that fond of each other. La Castilogne, played by Yvonne de Carlo, is the lover of firebrand Italian revolutionary Lucio Falengo (Georges Marchal). When Marchal's efforts to unite Italy result in his arrest and condemnation, La Castilogne offers herself to Napoleon in exchange for her sweetheart's life.