The story unfolds of the love-sick Nemorino, whose heart is longing for Adina, the beautiful town Librarian.
She, of course, spurns him, claiming not to love any one man and also, a little disdainful of Nemorino’s propensity toward moping and sighing.
She meets Sargent Belcore and uses him as a way to punish Nemorino. Meanwhile, ‘Doctor’ Dulcamara, a salesman and charlatan arrives in town selling an elixir that he promises will cure anything.
Nemorino asks him if he has a love potion and the doctor sells him a potion. He tells Nemorino that it will take 24 hours to go into effect and Nemorino takes the potion. In anticipation of the success he will have in 24 hours, he ignores Adina and this angers her. Wanting to punish him, she agrees to marry the Sargent that very day.
The second act finds Adina making wedding preparations, but irked that Nemorino is nowhere to be found. Nemorino is in despair because the potion will not have time to take effect before the wedding. The doctor advises another dose of elixir, Sargent Belcore advises Nemorino to join the army in order to pay for it. He does, and proceeds to drink more of the elixir.