Adina, a wealthy young woman, reads the workers on her farm an amusing story of how Tristan won Isolde’s love with the help of a magic potion. The bumpkin Nemorino adores Adina, but he’s too shy to speak to her. The conceited Sergeant Belcore arrives and proposes to Adina. Nemorino then approaches Adina, who tells him to go and live with his rich but ailing uncle. He replies that he cannot live without her.
In the village square, Dr. Dulcamara hawks his cure-all elixir. Nemorino naively asks the Doctor if he carries Tristan's love potion. Dulcamara sells Nemorino a bottle of Bordeaux. When Adina enters, Nemorino no longer seems interested in her. To test him, Adina agrees to marry Belcore, and she invites the village to her wedding party that very night.
At Adina’s marriage to Belcore, Nemorino is near despair. He asks Dulcamara for more love potion; but the boy, alas, is broke. To get more money to buy more elixir, he signs up as a soldier in Sergeant Belcore’s platoon.
Meanwhile, the village girls receive news that Nemorino's uncle has died, leaving him a fantastic inheritance. They shower Nemorino with affection; Nemorino thinks it’s because of the magic potion. Adina is upset to discover the other girls fawning on Nemorino. The doctor tries to sell her some elixir, but she declines. She purchases Nemorino’s army contract back from Belcore and admits to Nemorino that she loves him.
The next morning, Dulcamara announces that Nemorino's uncle has died, making the young peasant the village's richest squire. The Doctor credits his elixir with Nemorino's good fortune, and the peasants eagerly purchase it.