Abstract: Sis the title of John Updike’s unusual novel. This novel was the third in the Scarlet Letter Trilogy. The title itself arouses curiosity. Why only S? What does it stand for? One gets the answers only after reading the novel. The novel is in the form of letters sent by a woman to her husband, daughter, mother and a friend. She signs the letters by different names. To her husband she is simply S. To others she is either Sarah Worth or Kundalini or simply K. She is the protagonist of this novel.