After a shipwreck, twin siblings Viola and Sebastian wash up on the shores of Illyria. Viola, disguised as a man named Cesario, takes up service with the Duke Orsino, who is madly in love with the Lady Olivia. But Olivia is in mourning over her brother's death, so Orsino sends Cesario over as an emissary of love, except that Olivia falls for Viola!