A storm occurred on the sea, whilst Viola and her identical twin brother Sebastian were sailing on the sea. The storm ruined the ship and Viola and Sebastian were separated. Viola then floated ashore in a place named Illyria, she then decided that she would disguised herself as a man, named Ceasario.
Ceasario then gets job working for Orsino, the Duke. Orsino likes Olivia, who is mourning for her dead brother and has said she wont love for 7 years. Orsino sends love letters to Oliva and asks Ceasario to take them to her. When Olivia sees Ceasario she immediately falls in love with "him". Oliva ignores Orsinos letters and conserntrates on finding more out about Ceasario. But little does she know she is not a boy, she is a girl.
Meanwhile Violas twin brother, Sebastian, washed up onto the sand of Illyria. A man named Antonio rescued him from the beach. Antonio continues to help Sebastian. Back at Olivia's house her uncle, Sir Tony Belch, has convinced Sir Andrew Aguecheek that he could be a suiter to Olivia. There has been an ongoing feud between Marvolio and Belch, but with the help of Olivia's maid, Maria, Belch plots to make a fool out of Marvelo. this letter will make Marvelo think Olivia has fallen for him.
Marvolio falls for the letter but Olivia loves Ceasario, Ceassario is trying to make Olivia change her ind and fall in love with Orsino. Viola prepaies for A duel with Sir Andrew, Antonio enters and starts intervining and consequently is arrested. Viola does not recognise Antonio and Antonio thinks she is Sebastian.
Later belch and Sir Andrew encounter Sebastian, and when he was challenged but he was beat. Olivia then gets involved thinking he is Ceasario and asks him to marry her. Sebastian was very confused but decided that it would be the best thing for him as she is rich.
In the end Orsino and Viola declare their love for each other, Olivia and Sebastian will remain weds, Marvolio says he will seek revenge on the whole lot, Belch agrees to wed Maria and Marvolio is the only person to end up not in a relationship.