ACT I, Scene 1
Shortly before dawn, a band of musicians recruited by Fiorello gathers in front of a house in Seville. Count Almaviva has engaged the band to accompany him as he serenades an unknown beauty who lives there.  When the musicians are generously paid after the performance, they practically mob the Count in their over-effusive gratitude.

Left alone after the band has left, the Count hides as he hears someone approach.  It turns out to be Figaro, singing of his grand life as master-of-all-trades.  He is in demand everywhere, happily serving gentlemen and ladies in every capacity. Recognizing Figaro, the Count explains why he is there: he has seen and fallen in love with a beautiful girl whom he has never met.  He is pretending to be a poor student called Lindoro, because he wants to be sure that the girl loves him not just for his title and his wealth. 

Figaro has good news.  He knows the house well; it belongs to a foolish old doctor by the name of Bartolo, and Rosina is his ward.   Rosina appears on the balcony, and drops an encouraging note to her “Lindoro”.  Enraptured, the Count demands that Figaro find a way to get him into Rosina’s house.  Inspired by the promise of generous pay, Figaro proposes that the Count gain admittance by appearing in the guise of a drunken soldier, assigned to be billeted there.

ACT I, Scene 2
Alone, Rosina writes another note to Lindoro, as she sings of her determination to outwit her guardian and win the day. Dr. Bartolo arrives, suspicious of Rosina and infuriated by his two incompetent servants. He is eager to marry his ward and get his hands on her ample dowry.

Next on the scene is the schemer Don Basilio, who doubles as Rosina’s music teacher. Basilio reports that Count Almaviva is in town and is pursuing Rosina. Basilio has a plan to disgrace the Count and drive him away by spreading a scandalous rumor about him. Bartolo dismisses the idea, and insists that he will marry Rosina at once. He and Basilio retire to the doctor’s study to draw up the marriage contract. 

Figaro has overheard Bartolo’s conference with Basilio, and now he reports to Rosina all that took place. Rosina leads the conversation around to the interesting man whom she saw from her balcony.  A fine young fellow, says Figaro, and deeply in love too. He would be here in a moment, says Figaro, if only Rosina could bring herself to write him a little note.  After toying with Figaro for a while, Rosina produces the note – already written.  Figaro can only ruminate on how impossible it is to figure women out.

Bartolo returns, and confronts Rosina with a host of suspicions. Why is her finger stained with ink? Writing paper missing? The quill pen sharpened? Convinced that she is lying, he warns her not to trifle with him, and threatens to have her locked in her room for as long as he wishes.

Now the Count arrives, disguised as a drunken soldier just as Figaro planned.  Bartolo insists that soldiers cannot be billeted in his house, because he has a letter of exemption.  The Count manages to slip Rosina a note while Bartolo searches for the document. When he finds it, the Count contemptuously sweeps it aside. Tempers flare, and a battle is about to take place.  Even Figaro, who turns up at the height of the tumult, is unable to restore order.  Suddenly, a  portentous knock announces the arrival of the police. As the Count is on the point of being arrested, he reveals his identity to the officer in charge. The police withdraw. All are frozen for a while in astonishment, and then everyone erupts in confusion as the act ends.

ACT II
The Count makes another attempt to enter Bartolo’s house, this time pretending to be a substitute music teacher filling in for an ailing Don Basilio.  He gains Bartolo’s trust by promising to help turn Rosina against the Count.  Rosina arrives for her lesson, and recognizes “Lindoro” at once.  The young couple manage to exchange a few private words as Bartolo dozes during the music.

Now Figaro turns up, intending to give Bartolo his regular shave. The doctor hands Figaro his keys, and sends him off to get the necessary towels from the linen closet. While on this errand, Figaro steals the key to the shutters in Rosina’s room. 

Bartolo is about to be shaved when, to everyone’s embarrassment, Don Basilio appears. Everybody tries to convince Basilio that he is desperately ill, and a generous bribe from the Count persuades him to play along.  After many delays Basilio finally leaves, and the shaving begins. As Figaro keeps Bartolo distracted, the Count whispers to Rosina that he and Figaro will be back at midnight to take her away. Suddenly, Bartolo jumps up from his chair; he has overheard enough to know he’s being duped.  In a rage he chases the three conspirators out.

Bartolo’s aging maid, Berta, complains about the plight of the old spinster whom no one loves.  Meanwhile, Basilio has returned.  Bartolo wants to marry Rosina at once, and sends Basilio off to get the notary. Next, by a ruse, the doctor manages to convince Rosina that her Lindoro is unfaithful.  Lindoro is Almaviva’s agent, says Bartolo, and intends to steal her for the Count.  Heartbroken, Rosina reveals that the plotters are returning for her at midnight. Bartolo, determined to stop them, goes off to get the police.

In a raging storm, Figaro and the Count use the stolen key to enter Rosina’s room. Angrily, Rosina accuses Lindoro.  “You feigned love for me,” she says, “just to sell me to that vile Count Almaviva!”  “But, my dearest,” he tells her, “I am Count Almaviva!” The lovers are joyously reconciled, and prepare to make their escape.

Now Basilio arrives with the notary.  Brandishing a pistol to silence Basilio’s objections, the Count signs what was to have been Bartolo’s marriage contract.  Just as Rosina adds her signature, Bartolo appears with squad of police.  It is too late; Bartolo realizes he has been a fool, and all rejoice.