Chérubin is the young page of Count Almaviva who has just received a commission in the army and The Philosopher, his teacher, tells the servants that there will be celebrations. Also the famous Spanish dancer L’Ensoleillad is invited to the party. Nina, the Countess's maid, tells the Philosopher that she is in love with Chérubin. When Chérubin arrives he secretly slips a love letter to the Countess. The then tells the Philosopher that he is in love with both the Spanish dancer and the Countess. All of a sudden, the Count bursts in the room and threatens to kill Chérubin since he has discovered the secret love letter he had given to the Countess. But is Nina who saves the page's life when she proves the letter to be addressed to her by reciting every word written in the secret letter. The Count excuses himself to the Countess. However, The Philosopher hears Chérubin affirming once again that he loves both L'Ensoleillad and the Countess.
Je suis gris!, Chérubin's Aria
Lorsque vous n'aurez rien à faire,Nina's Aria
At an inn in the castle surroundings, the travellers are complaining to the Inkeeper about the poor quality of their rooms. Among them, also the Countess and the Baroness are not happy. Officers arrive to celebrate Chérubin's commission and when Chérubin arrives, he starts flirting with Captain Ricardo's mistress, so Ricardo, offended, challenges Chérubin to a duel. L'Ensoleillad arrives, postponing the duel for a while but soon, Ricardo and Chérubin begin to fight. The Philosopher intervenes and succeeds at dividing the two of them, leaving Chérubin free to seduce L'Ensoleillad. Since Chérubin serenades her standing outside her balcony, which is next to the balconies of the Countess and the Baroness, all the three women think that his song is really addressed to her, and each drops him a keepsake. The Duke, the Count, and the Baron understand that Chérubin is pursuing their wives, and they challenge him but Chérubin flees.
Outside the inn, Chérubin prepares for the three duels awaiting him, and writes his last will. The Philosopher arrives and teach him different fighting techniques. Determined to discover whom he was serenading the previous night, the Countess and the Baroness come from the inn looking for Chérubin. He confesses to them that his song was for L’Ensoleillad. The Count and the Baron then call off their respective duels and Chérubin sees L’Ensoleillad leaving the inn without even acknowledging him. When Nina tells Chérubin she is going to enter a convent because he doesn’t love her back, Chérubin realizes she is in love with her.