Olivia and Maria are in the garden, and Olivia is making plans to entertain Cesario; she sent him an invitation, and he has promised to come to visit her. She is very excited at the prospect and wonders how to treat him, how to "feast him." She is afraid that he will think that she is trying to "buy" him. Where is Malvolio, she wonders; he is usually grave and polite and can be counted on to calm her nerves.
Smiling foolishly, Malvolio enters. His whole appearance has changed since we last saw him; his dark clothes are gone, as is his dour appearance. Maria's forged love note has changed him from being "sad and civil" into being a merrily smiling fabrication of a courtier; he complains a bit about the cross-gartering causing "some obstruction in the blood," but he suffers gladly — if it will please Olivia. Smiling again and again, he kisses his hand and blows his kisses toward Olivia. She is dumbfounded by his unexplainable, incongruous dress and behavior, but Malvolio doesn't seem to notice. He prances before her, quoting various lines of the letter which he supposes that Olivia wrote to him, and in particular, he dwells on the "greatness" passage. Olivia tries to interrupt what he is saying, but to no avail; he rambles on and on until she is convinced that he must be suffering from "midsummer madness."
A servant announces the arrival of Cesario, and Olivia places the "mad" Malvolio in Maria's charge; in fact, she suggests that the whole household staff should look after him. Meanwhile, Malvolio, remembering the orders which Maria inserted into the letter, spurns Maria, is hostile to Sir Toby, and is insulting to Fabian. He finally drives them all to exasperation and fury, and when he leaves, they make plans to lock him up in a dark room, a common solution for handling a lunatic in Elizabethan days. Olivia won't mind, says Sir Toby: "My niece is already in the belief that he's mad."
