Figaro and Susanna are about to be married. The problem is that the Count has set his eyes on Susanna and wants to exercise the right of the first night — a medieval privilege allowing the master to take the bride before her husband. Figaro discovers the plan and swears to foil it. Meanwhile, Cherubino — the teenage page — is hopelessly in love with every woman in the castle and creates chaos wherever he goes.

Susanna and the Countess join forces against the Count. The plan: make the Count believe he has a secret rendezvous with Susanna, and send the Countess in disguise instead. In the middle: endless misunderstandings, people hiding behind chairs and windows, a page jumping out of a window, and the Count constantly made to look foolish without understanding why. The scene where the Countess forgives Susanna — and then asks forgiveness herself — is one of the most moving in all opera history.

In the garden at night, the chaos reaches its peak. The Count woos who he believes to be Susanna — but it is his own wife. He is unmasked, humiliated before everyone. The Countess, with extraordinary dignity, forgives him. The Count, for the first time, genuinely kneels and apologises.