This scene introduces us to the Duke, who is in love with a girl called Olivia. His servant goes to ask her whether or not she would like to go out with the Duke. The message back from her servant is that Olivia will not be seen in public for seven years because of the death of her brother.
After a shipwreck, Viola finds herself in Illyria, a coastal town. She believes that her brother has been killed in the shipwreck and that she will never get off this island. After learning about the Duke, she arranges with the captain of the ship to disguise herself and to serve the Duke. He may then fall in love with her.
Sir Toby and Maria are talking to each other about Olivia’s decision to morn for seven years. They are also talking about Sir Toby’s drinking and friend, Sir Andrew, a foolish knight that has been brought to the castle as a suitor to Olivia. Sir Andrew says he is going to leave, but Sir Toby persuades him not to, as Olivia is not interested in the Duke. Maria leaves, and Andrew and Toby dance.
Viola, already disguised as Cesario (she is referred to as Cesario instead of Viola throughout the play), has already become a servant to the Duke. Her first job is to try and persuade Olivia to go out with the Duke. Viola has fallen in love with the Duke.
Maria and Feste the clown are talking when Olivia enters with Malvolio. She has a conversation with Feste, and he gets the better of her. Maria announces that a young ‘man’ (Cesario) is here to see Olivia. She says that if he is from the Duke, she will not see him. Maria returns and says the young man will not take no for an answer, so Olivia meets him with Maria at her side.
Cesario is very convincing about the Duke’s love, but Olivia is not unstuck. She dismisses Cesario, and when by herself, shows that she is in love with ‘him’. She sends Malvolio with a ring Cesario apparently left behind and said he should return tomorrow.
Sebastian, Viola’s identical twin brother comes to shore after the shipwreck, saved by Antonio. He wants to be Sebastian’s servant, but he says that he will make it to the Duke’s court by himself. Scene Two Malvolio runs after Cesario to give him the ring. He denies that he gave it to her, and so Malvolio puts it on the ground in front of him. He (Viola) thinks that Olivia is in love with ‘him’.
Sir Toby and Sir Andrew are talking loudly. Feste joins them and sings a romantic song for them. The other two then join in. Maria comes down and tells them that they are making too much noise. Malvolio then enters and tells Sir Toby that if he doesn’t stop his drinking, he will be banned from the house by Olivia, his niece. He then leaves, as does Feste. Maria makes up a plan that she will leave a note that talks of Olivia’s love for Malvolio.
The Duke, still lovesick calls for some music. Feste arrives and sings a lovesick song back to him. He leaves, and Cesario and the Duke talk. Cesario is told to go back and try to woo Olivia.
In this scene, the note is set for Malvolio. Sirs Toby and Andrew and Fabian who hates Malvolio, watch him behind a tree. As Malvolio walks into the scene he is thinking about what it would be like to be married to Olivia. He finds the note and goes to do what the note says, which is to dress in yellow cross garter stockings.
In this scene, Cesario again goes to Olivia. She talks to Feste and Sirs Toby and Andrew. Olivia then comes out and confesses her love for Cesario. ‘He’ then runs away as Olivia continues to pledge her love.
In this scene, Sir Andrew is attempting to leave the castle, as he believes that Cesario has made more progress towards the love of Olivia. Sir Toby and Fabian persuade him to stay and convince Sir Andrew to challenge Cesario to a fight. Maria then enters and tells them all about Malvolio.
Antonio and Sebastian go to an Inn and Antonio gives Sebastian his purse in case he wants to buy something. Antonio reveals that he is in trouble with the Duke.
Olivia is pondering how she will invite Cesario to her house. Malvolio enters, and he is wearing yellow cross-gartered stockings. He seems to think that he and Olivia have some sort of understanding. He then leaves to let Cesario in.
Meanwhile, Sir Andrew shows Maria, Sir Toby, and Fabian his letter to Cesario. They urge him on. Sir Toby delivers the challenge to Cesario, and ‘he’ is very worried. Sir Toby tells Cesario that Andrew is the best fighter in the country. He tells Andrew the same about Cesario. They start to fight. Antonio sees this, and, mistaking Cesario for Sebastian fights for ‘him’.
He is then arrested by the police. He asks Cesario for his purse back, and Cesario doesn’t know what he is saying. He then calls Cesario Sebastian, which gives her/him hope. Toby and Andrew see this and are disgusted.
Feste goes to collect Cesario and sees Sebastian. He takes him to Olivia’s house mistaking him. When he gets there, Andrew hits Sebastian, also mistaking him. The latter then smacks Andrew. Toby draws his sword and is quickly beaten. Olivia comes out and shouts at Toby. She takes Sebastian inside, and he is in love with her.
Malvolio is locked up in the dungeon, as everyone thinks he is mad. Feste, dresses up as Sir Topaz the Curate, and goes and teases Malvolio. The latter asks for pen and ink, but Feste refuses. He then leaves.
Sebastian, although concerned about Antonio, can’t get over Olivia’s behavior. She then appears with a priest and asked Sebastian to marry her, mistaking him for Viola. He agrees.
This long scene brings into conclusion all of the plots and the sub-plots. Feste and Fabian are discussing a letter when the Duke enters to court Olivia in person. Antonio enters with his guards. Viola(Cesario) points out that was the man that saved her from Andrew. The Duke recognizes Antonio for his past troubles as a pirate and demands an explanation. He says that he and Sebastian were inseparable for the last three months.
Cesario has been working for the Duke for the last three months, and so Antonio is mad. At this time, Olivia enters and calls Viola tardy, and rejects the Duke’s love. Viola and the Duke turn to go, but Olivia calls Viola husband. The priest backs this up. Sirs Andrew and Toby enter and say Cesario beat them. Sebastian enters and tells Antonio not to worry, and all stare at the twins before them.
Viola and Sebastian are reunited. The Duke pleads his love to Viola, as Olivia is married. Feste enters with Malvolio’s letter, and Malvolio is called for. Malvolio calls Olivia a liar for writing that letter.
She says that it was written by Maria. Fabian confesses the plot to Malvolio and says that Sir Toby is married to Maria. Malvolio vows his revenge on ‘The whole lot of you’, and Feste finishes the scene and plays with a song.