In a square in front of Bartolo’s house a band of musicians are performing a serenade. Lindoro, who is the young Count Almaviva in disguise, tells beautiful Rosina about his love. Rosina is the young ward of the grumpy, elderly Bartolo and she is allowed very little freedom because Bartolo plans to marry her. Figaro the barber, who knows all the secrets and scandals of the town, arrives. Figaro devises a plan: the count, disguised as a drunken soldier who is quartered at Bartolo’s house so that he may arrange the meeting with Rosina.

Rosina recalls the voice that has enchanted her and resolves to overcome all obstacles on her way to happiness. She writes a letter to Lindoro and Figaro promises to deliver the note. Bartolo appears with Rosina’s music master, Don Basilio. Bartolo is suspicious of the Count, and Basilio advises to create false rumours about him. Almaviva arrives, disguised as a drunken soldier, and secretly passes Rosina his own note. Bartolo is infuriated by the stranger’s behavior and noisily claims that he has an official exemption from billeting soldiers. The civil guard bursts in to arrest Almaviva but when he secretly reveals his true identity to the captain he is instantly released.

Unsuccessful attempt does not prevent Almaviva from trying to meet his beloved once more. So the Count returns, this time disguised as Don Alonso, a music teacher and student of Don Basilio. Almaviva wants to speak with Rosina but Bartolo does not leave his ward alone with the new “teacher of music”. She sings an aria, and, with Bartolo dozing off, Almaviva and Rosina express their love. Suddenly Basilio shows up looking perfectly healthy, Almaviva, Rosina, and Figaro convince him with a quick bribe that he is sick with scarlet fever and must go home at once. While Bartolo gets his shave, Almaviva plots with Rosina to elope that night. But the doctor overhears them and furiously realizes he has been tricked again. Bartolo summons Basilio, telling him to bring a notary so Bartolo can marry Rosina that very night. A thunderstorm rages. Figaro and the Count climb a ladder to Rosina’s balcony and let themselves in with the key. Lindoro finally reveals his true identity as Almaviva. Basilio shows up with the notary. Bribed and threatened, he agrees to be a witness to the marriage of Rosina and Almaviva. Bartolo arrives with soldiers, but it is too late. Figaro, Rosina, and the Count celebrate their good fortune.