A shipwreck has separated identical twins, Viola and Sebastian. Viola is cast ashore in Illyria where, believing Sebastian drowned and fearing for her own safety, she disguises herself as her brother. Taking the name Cesario, she is employed by the young Duke Orsino as the go-between in the courtship of the recently orphaned Countess Olivia. Orsino and Olivia become increasingly obsessed with the "boy"; Olivia falls in love and Orsino cannot be out of "his" company. Olivia's hapless wooer, Andrew Aguecheek, is none to happy with Cesario and a duel is called. Cesario is saved by a man who turns out to be her brother Sebastian. Eventually, Olivia marries the real boy, Sebastian, and Orsino discovers that Viola/Cesario is the girl of his dreams.