Viola, disguised as a boy, goes to serve the Duke Orsino and falls in love with him. Orsino sends her to woo Olivia for him. Olivia falls for Viola’s male disguise. Viola’s twin, Sebastian, whom she thought was dead, returns and marries Olivia. Orsino realises Viola is a girl and marries her. Meanwhile Olivia’s relatives and household play a mean trick on her steward, Malvolio, and try to drive him mad.