Act 3

The Count is bamboozled by the events of the day and begins to doubt the Countess’ fidelity. He vows that Figaro will marry Marcellina. The Countess persuades Susanna to convince the Count of her secret desire for him and to arrange to meet him in the garden, where the Countess herself, dressed as Susanna, will consummate the plan. Fooled by Susanna, the Count overhears her tell Figaro that he is now sure of winning his case against Marcellina. The Count rages at the thought that Figaro will get what he wants and he himself will go without.

Don Curzio announces the Count’s decision: Figaro must marry Marcellina or pay her. Figaro says that he cannot marry without his parents’ consent, and that he does not know who they are. Marcellina recognises him by a birthmark on his arm as her own son Raffaelo, kidnapped in childhood. Bartolo is his father. Susanna catches Figaro embracing Marcellina, but soon learns the good news. The two couples will celebrate a double wedding.

Barbarina and Cherubino (to be disguised as a girl) plan to join the other girls in bringing flowers to the Countess. The Countess grieves at her humiliation at having to beg for a servant’s favour to save her marriage. She remembers how Almaviva used to love her, and hopes to regain his love.
Antonio tells the Count that Cherubino is still around the castle, now dressed as a girl.

The Countess dictates a note for Susanna to send the Count. Susanna seals the note with a pin. The girls present their flowers. Antonio and the Count catch Cherubino and are about to punish him when Barbarina interrupts them. During the wedding, Susanna slips the note to the Count, who pricks his finger on the pin.

Act 4

Figaro finds Barbarina searching for the pin the Count has given her to take back to Susanna. He suspects that they are planning a rendezvous. Figaro tells Marcellina that he is ruined: Susanna is unfaithful. Marcellina tells him to be patient, and plans to warn Susanna.

In the garden, Barbarina has arranged to meet Cherubino in secret. Figaro brings Bartolo and Basilio to witness Susanna’s seduction by the Count. Figaro gives a warning not to trust women. Susanna and the Countess dress as one another.

The Count courts the Countess, thinking she is Susanna, and leads her away. Figaro interrupts them and they separate and hide. Figaro pretends to court the disguised Susanna. The Count accuses them of treachery and calls everybody together. They all beg the Count to forgive the woman he thinks is his wife, but he refuses until the Countess herself appears. It is now the Count’s turn to beg for forgiveness.