Nemorino, a farmhand, is madly in love with Adina, a wealthy rancher. As he goes about his chores, he sees her reading and laments that she doesn’t seem interested in him. Adina, meanwhile, is engrossed in her book, when suddenly she bursts out laughing at the absurdity of the story. Nemorino asks her what she is laughing about, and Adina tells him the story. In the book she is reading, Tristan is in love with Isolde, who is not in love with him. A sorcerer gives Tristan the famous elixir of love, and after Tristan drinks the potion, Isolde falls in love with him.
Nemorino immediately sees that Tristan’s situation and his own are similar and wishes that he could find some magic elixir of love to make Adina fall in love with him.
Adina and Nemorino are suddenly interrupted by the sound of a spluttering engine and quickly see a plane that’s in trouble. Lower and lower it flies until suddenly it crash lands right into the big tree in Adina’s front yard. Fortunately, the pilot Belcore is not hurt, but he is stuck at the farm until his plane is repaired. Belcore immediately notices the pretty Adina and begins to flatter and woo her. After a few minutes, Belcore, much to everyone’s surprise, asks Adina to marry him and demands an immediate answer.
Nemorino is horrified but secretly wishes that he had Belcore’s confidence. Adina laughs off the proposal but offers Belcore a cold lemonade. Nemorino tries to stop Adina, but gets tongue-tied, and Adina rejects him unkindly and joins Belcore in the house.
Nemorino, devastated, leaves. Suddenly, a trumpet call is heard in the distance and Dr. Dulcamara, purveyor of dubious, medicinal compounds, (which he claims can cure measles, mumps, malaria, warts, aches and pains, chicken pox, and pretty much anything that ails you) arrives on the scene. Nemorino, hearing the doctor’s claims immediately thinks that perhaps Dr. Dulcamara might have the elixir of love that will make Adina fall in love with him.
After some initial confusion, Dulcamara realizes that he has an opportunity to make some money off Nemorino and claims that, “Yes, indeed, I have the amazing elixir of love!” Then he secretly puts some cheap wine into a medicine bottle and sells it to the eager Nemorino.
Dulcamara takes his leave and Nemorino decides to try the “elixir of love” at once. He takes an extra dose and becomes tipsy. Adina enters and expects that Nemorino will pay attention to her as he always has before, but instead he just ignores her. This strange behavior makes Adina angry. She decides to teach Nemorino a lesson and when Belcore comes out of the house, she immediately agrees to marry him. At once.
Nemorino begs Adina to wait until tomorrow, but she insists. Nemorino is now desperate and seeks out Dr. Dulcamara again for another dose of the elixir of love. Unfortunately, he does not have enough money and Dulcamara turns him down. Belcore overhears that Nemorino is short of cash and tells the desperate youth that if he joins the air force, he will receive an enlistment bonus. Nemorino agrees and instantly takes his money to Dulcamara for another dose of the “elixir” which Dulcamara happily sells him. Nemorino thinks he has it made. Adina seeing him confident and happy, realizes that she loves him herself.
Dulcamara sees Adina uncharacteristically sad and tells her that Nemorino has joined the air force just to purchase some elixir of love to make a girl fall in love with him. Adina realizes that the girl is her and knows what she must do.
Adina finds Nemorino and tells him that she has bought back his contract so that he doesn’t have to join the air force. Eventually, she confesses that she loves him and doesn’t want him to go. All ends happily with the new couple thanking Dr. Dulcamara and Belcore contenting himself with the fact that there are plenty of other girls out there in the wild blue yonder.