Viola discovers herself falling in love with Orsino a problematic love to follow, as Orsino considers her to be a man. But when Orsino directs Cesario to bring Orsino’s love communications to the scornful Olivia, Olivia herself begins to love the beautiful young Cesario, trusting her to be a man. It takes the form of the love triangle: Viola falls in love with Orsino, Orsino falls in love with Olivia, and Olivia begins to love Cesario and everyone is depressed.
In the meantime, there are different contributors of Olivia’s household, her unruly drunkard uncle, Sir Toby, his silly pal Sir Andrew Aguecheek, who’s struggling in his desperate way to court Olivia; Olivia’s humorous and attractive waiting-gentlewoman, Maria. When Sir Toby and the others become angry at Malvolio’s endless troubles to spoil their fun, Maria contrives a useful witticism to make Malvolio ponder that Olivia has fallen in love with him. She copies a letter, supposedly from Olivia, talked to her dearly loved (whose name is indicated by the letters M.O.A.I.), saying him that if he wishes to earn her approval, he should wear yellow leggings, act arrogantly, smirk continuously, and declines to describe himself to anybody. Malvolio discovers the letter accepts that it is talked to him and, occupied with dreams of a wedding with Olivia and he will become honorable himself, and he happily follows its orders. He performs so extraordinarily that Olivia begins to think that he is mad.
In the meantime, Sebastian, who is alive and he also begins to believe that his sister has died. He lands in Illyria along with his protector and friend, Antonio. Antonio has taken care of Sebastian since the wreckage and is fervently (and perhaps sexually) committed to the young man.
Sir Andrew, perceiving Olivia’s fascination towards Cesario (who is Viola in disguise), defies Cesario for a contest. Sir Toby, who perceives the approaching duel as amusing fun, provokes Sir Andrew on. Conversely, when Sebastian who appears just like the concealed Viola, reaches on the scene, Sir Andrew and Sir Toby end to blows with Sebastian, considering that he is Cesario. Olivia arrives amid the misunderstanding. When she meets Sebastian, she thinks that he is Cesario, she requests him to wed with her. He is perplexed since he has never observed her before. However, he realizes that she is rich and good-looking, and therefore, he is ready to marry her. In the meantime, Antonio has been detained by Orsino’s soldiers and now pleads to Cesario for comfort, misidentifying him for Sebastian. All of a sudden, Viola has found that her brother is alive.
Malvolio’s imaginary insanity has permitted the delighted Maria, Toby, and others to catch Malvolio into a dark, and a small room for his dealing and they irritate him at will. Feste becomes “Sir Topas,” a cleric, and acts to inspect Malvolio, asserting him definitely as an insane in spite of his complaints. Though Sir Toby starts to think of the joke, and they permit Malvolio to refer a letter to Olivia, in which he requests to be unconstrained.
Ultimately, Viola (still camouflaged as Cesario) and Orsino go to Olivia’s house, where Olivia greets Cesario as her husband, considering him to be Sebastian, whom she has just wedded. Orsino is manic, but then Sebastian himself seems on the scene, and all is exposed. The relations are blissfully united, and Orsino apprehends that he has fallen in love with Viola. Now he has come to know that he is a woman and requests her to wed with him. It is disclosed that Sir Toby and Maria have gotten married secretly. Lastly, someone recollects Malvolio, and he is released from the darkroom. The trick is exposed in full, and the disillusioned Malvolio leaves the joyful couples to their festivity.