Sally Porter is a drab waitress, divorcee, and loner in the great city. But, though she is unaware of it, she is also four other, quite different people: Nola, the cold independent artist who has a studio in Greenwich Village; Derry, the happy-go-lucky tomboy; Bella, the sexpot with a talent for singing and dancing; and finally Jinx, the hate- filled killer. Whenever events put too much of a strain on Sally Porter, she feels a headache and a blackout coming on -- and a new character takes over. If there is a man to be fascinated, she will become Bella. If there is an intellectual problem, she will become Nola. And -- as happens in the opening scene of the novel-- if there is a rapist to be dealt with, she becomes the vicious Jinx. It is the task of the wise and patient psychiatrist, Dr. Roger Ash -- a man who nevertheless has severe problems of his own -- to deal with this case of multiple personality and, through painstaking therapy, to try to fuse the four disparate personalities into "the fifth Sally." His struggle and near disasters become the major strand of the story. Sybil and The Three Faces of Eve were case histories dealing with multiple personality disorder. Although based on fact, this is the first contemporary novel, to deal with the theme as fiction.