It is Fadinard’s wedding day in Paris. As he hurries home in his carriage, to make sure that all the preparations are being carried out smoothly for his marriage to Elena, his whip gets entangled in a tree. While he is disentangling it, his horse passes the time with a little snack—a lady’s straw hat. Unfortunately, the lady who owns the straw hat is behind the tree, and even more unfortunately for Fadinard’s smooth-running wedding day, she is a married lady called Anaide and she is with her lover Emilio. They arrive at Fadinard’s house. Anaide is anxious and upset, because the straw hat was bought for her in Florence by her jealous husband, who will ask very awkward questions if she goes home without it. Fadinard sends his servant out to buy a replacement hat and the wedding party arrives: the bride-to-be Elena, her grotesquely comic father Nonancourt, and guests who create confusion wherever they go. Fadinard’s servant is unsuccessful in his efforts to find another hat, and as Emilio threatens Fadinard with a duel if he does not replace it, Fadinard decides that he must go out and obtain one.
Carrying the remains of the mistreated straw hat, Fadinard goes to a milliner’s shop where he learns that the last Italian straw hat has been sold to the Baronessa di Champigny. He rushes to her villa and is mistaken for Minardi, the famous violinist who is to give a recital and be the Baronessa’s guest of honor at dinner that evening. Fadinard is anxious to remain in the house and obtain the straw hat, so he does not correct the mistaken identity. The Baronessa says that she gave that hat as a gift to one of her friends, the wife of Beaupertuis, and when the wedding party arrives, causing trouble and confusion, Fadinard decides to make a quick getaway in pursuit of the Baronessa’s hat.
Fadinard’s luck continues to run out when he is told that Beaupertuis’ wife is not at home. Beaupertuis complains about his wife’s lateness; she went out that morning to visit her cousin and has not yet returned. Fadinard tells him his story and about his quest for the hat and begins to search the house thoroughly for the straw hat given by the Baronessa. Meanwhile, Nonancourt, and the wedding party arrive, looking for the bridegroom, having consumed a great deal of the Baronessa’s champagne. Fadinard learns that Beaupertuis’ wife is actually Anaide, and Bearpertuis is so enraged that he grabs a pistol and runs off to look for his faithless wife.
Everything is upset and it appears that the wedding of Fadinard and Elena will have to be called off. The wedding party has gotten lost in Paris and arrested; Beaupertuis still wants to kill his wife; Nonancourt wants to cancel the marriage and take Elena home. But a hat is discovered—the hat that the bride’s uncle, Vezinet, had brought as a wedding gift at the beginning of these events—and it is given to Anaide in time to convince her husband that, since she has a hat, she must be innocent. Fadinard is able to get free of the wedding party and other hinderances, and can begin to enjoy his life with Elena.