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, Antonio 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 towards the arbour. Figaro interrupts them, and they separate and hide. Figaro pretends to court the disguised Susanna, and gets slapped for doubting her. 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.