Sir John Falstaff, a slightly shabby chevalier almost beyond his prime, has left the brothels of London and has ended up in a tavern in Windsor: In dire need of new fundraising tactics, dissimilar to those crude methods he has so far been practising with his cronies Bardolfo and Pistola, Falstaff has an idea: In the houses of decent townsfolk, it is the women who take care of the money. That way he could mix business with pleasure. But first, Falstaff has to dispose of those – not unjustified – allegations of theft Dr. Cajus is confronting his servants with. Then it is high time to contrive the hanky-panky, which means that two letters have to be delivered to Meg Page and Alice Ford. For reasons of honour, Bardolfo and Pistola refuse to do it. This sets Falstaff off – and he fires them. Instead, the innkeeper takes care of the delivery.
The two ladies meet, with them Miss Quickly, a factotum who knows every trick in the book, and Alice’s daughter Nannetta. It becomes obvious that the wording of the two letters is exactly the same; thus the women decide to take Falstaff for a ride. Bardolfo und Pistola try to get in on it as Master Ford’s informers, Alice’s husband; there is Cajus too, chosen by Ford to be his daughter Nannetta’s groom; and also Nannetta’s young admirer Fenton tries to score. A great confusion ensues and in the end, the men resolve to not only outsmart Falstaff - but Alice too. In the midst of all that, the two young people Fenton and Nannetta manage to sing about their love.
The seemingly rueful Bardolfo and Pistola return to Falstaff. Miss Quickly tells Falstaff what he wants to hear: that both women are in love with him, that they keep this secret from each other and that Alice would have time for him between two and three o’clock. Shortly afterwards the disguised Ford appears, who, under the name of Fontana and by making use of a big bottle of wine and lots of money, brings forward his somewhat absurd concern: He is unhappily in love with Alice, who keeps acting chaste. But if Falstaff seduced her and thus set a precedent, he maybe would have a chance with her too. Falstaff admits that this is about to happen anyway. An outburst of jealousy in tragic style by Fontana-Ford ensues.
The four women are preparing everything for Falstaff’s welcome. Meg is supposed to burst in and interrupt the rendezvous, so that Falstaff – allegedly evading the arrival of the jealous husband – would end up eventually in a clothes basket full of rejected laundry that is about to be disposed of into the Thames. Beyond that, the women have a second task: to prevent Ford’s plan to marry Nannetta to Cajus.
Falstaff appears, the classic old style charmer. Alice provokes him to badmouth Meg. Miss Quickly and Meg appear, pretending to be appalled. Falstaff hides behind a folding screen. Suddenly there is real commotion: Ford, the other men and some neighbours storm in, looking for Falstaff, who seeks shelter in the laundry basket. The young couple slips behind the unoccupied folding screen. When the men hear the sound of a kiss coming from there, they believe to have caught Falstaff and Alice red-handed. That it is Fenton and Nannetta kissing pleases neither Cajus nor Ford. In the ensuing chaos Alice has Falstaff thrown out of the window into the river, thus proving to her husband that she has in fact no interest in the chevalier.
Falstaff is deeply hurt, but reinstates his balance over some warm wine. Between the acts, some sort of deliberation must have taken place in Ford’s house: because now, the men and women of Windsor have decided to join forces to make Falstaff look a fool. Eventually Miss Quickly manages to convince Falstaff that his painful fall was not Alice’s fault and succeeds in persuading him to dress up as the Black Huntsman - with deer's antlers on his head - to meet Alice at midnight at the cursed area of Herne's Oak.
The people of Windsor agree on their respective costumes. Ford urges Cajus to remember Nannetta’s costume and to approach her at night, so that he, Ford, can then seal the marriage at once. Luckily, Quickly has overheard the conversation. Fenton wallows in self-pity, but the women set him straight and arm him with all necessary instructions.
Falstaff appears. Alice and Meg manage to confuse him a bit. Nannetta, dressed up as the Fairy Queen, interrupts the threesome. The spoof begins. The men arrive, stage some sort of exorcism and expose Falstaff. Ford wants to wed the couple Cajus-Fairy Queen. Alice asks Ford to wed a second couple as well. Ford agrees. When the veils are finally taken off, they discover Bardolfo under the Fairy Queen’s veil, holding Cajus’ hand. Nannetta and Fenton are husband and wife. Final scene: All the world is folly but also: All the world is villainy.