Falstaff and Mistress Quickly talk at the Garter Inn. He says he'll keep his third appointment with Mistress Ford, but he hopes that things will work out this time. Quickly departs to prepare, and Ford, in disguise as Brooke, enters. Falstaff tells Brooke that things will be decided that evening in the park at midnight, near Herne's oak. Brooke asks Falstaff about the previous day's adventure with Mistress Ford. Falstaff says that he had to be disguised as a woman, and Mistress Ford's madman husband beat him. Now he wants revenge on Ford, he says.
Page, Shallow, and Slender prepare for the evening's events. Page reminds Slender that his daughter will be wearing white. Mistress Ford, Mistress Page, and Caius prepare as well. Mistress Page tells Caius that her daughter is in green and sends him to look for her. Mistress Page says that her husband will be unhappy about the marriage between Anne Page and Caius, but that's too bad. The women look forward to frightening and mocking Falstaff later that night. They head out to Herne's oak. Evans leads the children, all in disguise, to their hiding spot near the oak.
Falstaff arrives at Herne's oak in disguise as Herne with large horns on his head. He ruminates about the Greek gods, who disguised themselves as animals to seduce women. Mistresses Ford and Page enter. Falstaff embraces Mistress Ford and is delighted that Mistress Page is there too. They hear a noise, and the ladies flee. Evans enters with many children in disguise, along with Mistress Quickly disguised as the fairy queen and Anne Page disguised as a fairy. Shouting to each other, they speak of magic and the supernatural. Falstaff is terrified; he falls to the ground and hides his face.
Mistress Quickly enthusiastically takes on her role and speaks eloquently of fairies and potions, flowers and gems. Evans says that he smells a man. Quickly says they'll set him aflame, and if he burns, then he'll prove to be corrupt. They burn Falstaff with candles, and Quickly declares him corrupt. The children chant as they encircle Falstaff and pinch him.
Meanwhile, Caius sneaks off with a boy wearing a white outfit, and Slender steals away with a boy wearing green. Fenton and Anne run off together. Finally, all the children in disguise run away. Falstaff gets up and tries to run away, but Ford and Page and their wives appear. Page says that they have caught him in the act of trying to seduce their wives. Ford reveals to Falstaff that he was Brooke, and that he plans to take Falstaff's horses in return for the money he lent Falstaff while playing the role. Falstaff realizes that he's been made into an ass. He asks if the fairies really weren't real.
Evans tells him that the fairies won't bother him if he serves God instead of his desires. Evans advises Ford to leave behind his jealousies, too. Ford says he won't distrust his wife until Evans can speak good English. Falstaff is upset to be scolded by Evans, a man who so mangles his native English language. Mistress Page asks Falstaff if he really thought they would have consented to lose their honor for him, such an unattractive drunken old man? Falstaff admits that he is defeated and that they can do what they want with him. Ford says they'll take him to Windsor and make him pay back his debts.