'Twelfth Night, or What You Will' is a romantic comedy by William Shakespeare. The play centers on the twins Viola and Sebastian, who are separated in a shipwreck. Viola (who is disguised as Cesario) falls in love with the Duke Orsino, who in turn is in love with Countess Olivia. Upon meeting Viola, Countess Olivia falls in love with her thinking she is a man.