The document provides a summary of the plot of Shakespeare's play Twelfth Night. It describes the main characters and their relationships: Duke Orsino loves Lady Olivia but she refuses him while in mourning. Twins Viola and Sebastian are separated in a shipwreck, with Viola disguising herself as a man named Cesario to work for Duke Orsino. Orsino sends Cesario to woo Olivia, but Olivia falls for Cesario instead. Sebastian is later mistaken for Cesario, further complicating the relationships and identities of the characters. Themes of love, disguise, and madness are also explored through the interactions and deceptions between characters.