The plot focuses on mistaken identity. Masquerading as a young page named Cesario, Viola enters the service of Duke Orsino, who is in love with Olivia. When she rejects his romantic advances, Orsino decides to use Cesario as an intermediary. Olivia, believing Cesario to be a man, falls in love with the attractive messenger. Viola, in turn, falls in love with the Duke, who also believes Cesario is a man and regards him as his confidant.