Orsino is informed that Olivia is mounring the death of her brother and refuses to hear the Duke's vows of love.
Act 1, Scene 1
Viola is shipwrecked and saved, but there is no news about her twin brother Seb. She decides to disguise herself as a young man and seeks employment in the Duke's court in Illyria.
Act 1, Scene 2
Sir Toby Belch moves into Olivia's house and is very rowdy. Maria warms Sir Toby that his actions will get him in trouble, but he takes advantage of Olivia's hospitality.

Sir Toby's friend, Sir Andrew, decides not to pursue his courtship of Olivia any further. Toby encourages him not to give up.

Act 1, Scene 3
Viola, disguised as Cesario, works for Orsino, who quickly develops a deep affection for him and tells him his feelings for Olivia. Orsino sends Viola to Olivia with his message of love, while Viola herself falls in love with Orsino
Act 1, Scene 4
Maria yells at Feste for his abscence. Olivia enters with Malvolio who criticizes Feste's good humour, but Olivia defends Feste and criticizes Malvolio's sour personality. Viola arrives, but Toby (drunk) stops him from entering and Malvolio is sent to send Viola away, but Viola's stubborness arouses Olivia's curiosity, so she decides to see Viola.

Viola delivers a really good speech for Orsino's love, but Olivia isn't convinced. She ends up falling in love for Viola. She rejects Orsino's message, but she sends Malvolio after Viola to return a ring that "belong to" Viola, but Olivia just wants to make sure Viola comes back.

Act 1, Scene 5
Seb believes that Viola is dead.

Antonio, aother kind and generous sea captain, has landed safely on the coast of Illyria with Seb and decides to accompany Seb to the court of Orsino despite the great danger.

Act 2, Scene 1
Malvolio catches up with Viola, as instructed by Olivia, to "return" the ring. Viola resists taking the ring and is puzzled by Olivia's deception, but then realizes that she has fallen in love for her.
Act 2, Scene 2
Toby and Andrew continue to spend their nights drink and Feste joins when and sings a song about the pleasures of young love. Maria comes to warn them that Olivia is getting even more displeased, but they ignore her advice.

Malvolio enters and gives them a formal warning and threatens to report Maria to Olivia, for her assumed participation. Maria reveals a plan to trick Malvolio by playing with his arrogance and ambition. She is also aware that he loves Olivia. She plans to write a love letter in Olivia's handwritting in order to get revenge on Malvolio

Act 2, Scene 3
Orsino continues to suffer from unrequited love.

Feste sings him a tragic ballad about the a rejected lover. Meanwhile, Orsino lectures Viola about love, claiming that men and women love in very different ways. Viola almost tells Orsino her love for him, but her disguise as Orsino protects her from discovery. At the end of the scene, Orsino sends Viola back to Olivia on his behalf.

Act 2, Scene 4
Toby, Andrew, and Fabian hide in a bush in Olivia's garden to watch Maria's plan unfold. Malvolio enters, daydreaming about his future with Olivia.

He is completely fooled by the letter and decides to obey every instruction said in the letter. The listeners congratulate Maria.

Act 2, Scene 5
Viola returns to Olivia's house and in the garden, she meets Feste and engages in a brief battle of wits with him. When Feste leaves to summon Olivia, Toby and Andrew has a conversation with Viola.

Olivia enters and dismisses the others so she can be alone with Viola. She rejects Orsino's offers of love again and she openly revelas her love for her (Cesario/Viola). Viola expresses only pity for Olivia's feelings and swears she will never love a woman.

Act 3, Scene 1
Andrew sees Viola and Olivia together in the garden and decides to abandon his courtship of Olivia. Toby and Fabian convinese Andrew that Olviai was trying to make him jealous by being friendly to Viola. They encourage him to challenge Viola to a duel, saying that courage is the best way to win a woman's heart.

Maria enters to reveal that Malvolio has fallen for hte trap completely and is wearing yellow, cross-gartered stockings with a huge smile on his face. They run off to see the fun.

Act 3, Scene 2
Seb and Antonio arrive in Illyria, but Antonio is wanted in Illyria so he is afraid of being seen. He rejects Seb's suggestion that they tour the city, but does not want to spoil his fun, so he gives him his wallet should he want to buy a souvenir. Antonio intends to go directly to the Elephant Inn to make arrangements for their food and lodging.
Act 3, Scene 3