Sebastian and Viola were twins and loved each other. It was impossible to distinguish between them if they dressed alike. But they were separated by a storm while sailing down the coast of Illyria. Viola reaches the shore and becomes Cesario, disguised as a boy, deciding to serve as a page to the Duke of the land who was in love with Olivia. She was sent to Olivia to convey Duke?s love for her but Olivia at their first meet starts loving Cesario. But Viola had started to love the Duke! At this time Sebastian along with Antonio, a sea captain, had arrived in the same city. Viola had to face the problem of being challenged for a fight by Sir Andrew Aguecheek, friend of Sir Toby Belch who was Olivia?s uncle. As the duel starts between them a stranger comes to the rescue of Viola. He was Antonio and had mistaken Viola for Sebastian and won the duel for her. Antonio had once wounded Duke?s nephew in a sea-fight and so when the Duke?s officers came to arrest him he asks Viola to give him back his purse, as he may need it now. But he was a complete stranger to Viola and so she couldn?t return his purse. This disappointed Antonio. As they left, Sebastian came there and this resumed the fight with Sir Andrew. The news of this fight reached Olivia and she put an end to this fight and called for a priest who arranged her marriage with Sebastian. Duke lost his patience and decided to speak to Olivia personally but at this Olivia declared her love for Cesario and called him her husband at which Duke felt angry and he made his way back. At this moment Sebastian enters and everyone goes dumbstruck gazing at Sebastian and Viola. They both recognize each other and get united after such a long wait. This explained things like whom Olivia had actually married. Antonio?s thought about the ingratitude that Sebastian did proved wrong. Duke found that he could never get Olivia?s hand in marriage and he remembered how Viola had served him lovingly and so asks her hand in marriage. Viola who got her brother back, joyously agreed to marry.
Thus the story ends with the unity of the twins and their marriage with the ones they loved.