19 parts Complete "Twelfth Night; or, What You Will" is a comedy by William Shakespeare, believed to have been written around 1601-02 as a Twelfth Night's entertainment for the close of the Christmas season. Viola is shipwrecked on the coast of Illyria and she comes ashore with the help of a captain. She loses contact with her twin brother, Sebastian, whom she believes to be dead. Disguising herself as a young man under the name Cesario, she enters the service of Duke Orsino through the help of the sea captain who rescues her.