In 16th-century Italy, the childless marriage of Prince Don Vincenzo Gonzaga and the Princess Margherita Farnese of Parma arouses court gossip. Defenders of the prince maintain that he is an extremely virile man burdened with a barren wife; detractors claim that his marriage has never been consummated because of his impotence. The prince's father, the Duke of Mantova, is concerned that his family will have no heir and arranges for the marriage to be annulled. To form a powerful and financially helpful alliance, the duke seeks to marry his son to Princess Eleanora dei Medici, the daughter of the wealthy rulers of Florence, but the Medici refuse to consent to the union until the prince proves his manhood. The prince angrily refuses to submit to their demand and consoles himself with his mistress and with the recently widowed Marchesa of Pepara. His father retaliates by cutting off his allowance, and the prince reluctantly agrees to a test. The Medici select a young virgin, Giulia, school her in the ways of love, and then present her to the prince. Unnerved by the presence of witnesses, the prince is unable to respond to Giulia's seduction attempts. As his time runs out, however, he overcomes his self-consciousness and establishes his manhood. Triumphant, he walks to the bedchamber window and acknowledges the cheers of the crowd below.
