A village at harvest time. The villagers are enjoying a siesta. Nemorino admires from afar the beautiful Adina who takes an interest in the arts and is reading the legend of Tristan and Iseult and having a good laugh at the story of the love potion. She even reads the story to the peasants. Thereupon enters Sergeant Belcore at the head of his squadron. During a public seduction scene he proposes to Adina. The young woman asks him to wait a while and offers him refreshments. Nemorino, hurt, declares his love, and declares that he is willing to die for Adina. However she discourages him. She is fickle and does not want to love him. Doctor Dulcamara, a barker, arrives upon the scene. He sells a magic elixir that cures all ailments from wrinkles to diabetes and even paralysis. Nemorino has an idea: the peddler must surely possess Queen Iseult’s love potion.

Dulcamara, delighted to come across such an idiot, confirms that he has it. He sells Nemorino a small bottle of Bordeaux and promises him that he will feel the effects within twenty-four hours. (Just the time he himself will need to leave the village.) An overjoyed Nemorino tests the potion and finishes the bottle. Convinced that he is feeling the first effects of the elixir and that Adina will soon fall in love with him, Nemorino feigns indifference. A furious Adina agrees to marry Belcore within six days. Nemorino remains unperturbed.

The potion will take effect by the next day. However, unexpected complications oblige Belcore to leave for the war the next day. Adina decides to marry the soldier straight away. Nemorino, who has now sobered up, begs Adina to wait. However the latter, offended, invites the whole village to the wedding. Nemorino is grief-stricken.  

The wedding party is in full swing. The guests drink, joke and sing. Nemorino has stayed away and Adina is disappointed. Everyone steps outside for the signing of the wedding contract leaving Dulcamara alone at the buffet. Nemorino arrives, on the verge of suicide. Dulcamara advises him to take another dose of the potion. But Nemorino has no more money and resolves to join the ranks alongside Belcore to be able to afford another bottle of the magical Bordeaux.

The village girls have heard that Nemorino’s uncle has died. He has inherited a fortune. All of a sudden they find Nemorino very handsome and become very friendly with him. “It’s the magic potion” thinks the peasant who has finished the second bottle. Adina, observing Nemorino’s success and discovering that he has joined up in order to win her love, at last decides to give him her love. Dulcamara offers her a little of the magic potion but Adina places all her trust in the power of her eyes.

Nemorino, who has seen Adina’s distress, is delighted. Adina hands him his enlistment forms that she has bought back from Belcore and, at last, falls into his arms. Belcore consoles himself with the idea that there are plenty of other women in the world. The villagers fall over themselves to buy Dulcamara’s marvellous potion that brings love and riches.