The Twelfth Night Summary Act IV
The comedy now twists and turns in a series of confusing events as Sebastian is mistaken by all and sundry for Cesario (Viola). Sir Andrew on finding Sebastian hits him thinking him to be Cesario but Sebastian a well built man retaliates to the horror of Sir Toby who stops him. When Sir Toby begins to fight with Sebastian, Olivia screams at him to stop. She pleads with Sebastian to forgive Sir Toby for his misdemeanor and Sebastian is now thoroughly confused
He is totally taken up with the beautiful woman who mistakes him for her lover and he too falls in love with her. They get married secretly in a chapel.
Meanwhile more comical events unfold with Feste the clown teasing Malvolio in a dark room where he is being kept under suspicion of being mad. Ultimately fester allows him to write to Olivia mentioning that he is a sane man.