The libretto, by Léon Battu and Ludovic Halévy, is based on Sheridan's play Saint Patrick's Day.

The mayor and his wife Véronique are woken up very early one morning by what appears to be a noisy advertising campaign outside their house, shouting the talents of a Doctor Miracle.

This is, in fact, a young officer, Silvio, who had thought up this ruse in order to be able to serenade the mayor's daughter Laurette, with whom he has fallen in love.

Laurette sings of her passion for Silvio, and a young man suddenly arrives at the house: he says that he is Pasquin and that he has been sent by a friend of the mayor to help out with the housework – he adds that he is allergic to soldiers.

Thoroughly outwitted, the mayor offers Laurette to Silvio and the opera ends in an ensemble in which they all agree that the phony doctor did after all have the cure for everything, which is Love.