The compelling and compassionate first-person account of a psychologist's work with multiple-personality patients. Mayer, a New York City psychologist, writes of his calling with all the wisdom and fervor of a prophet crying in the wilderness--and a wilderness it is that his patients inhabit, not only for their tortured state but also for the deaf ear that the psychological establishment usually turns toward them. ""There is no such thing as multiple personality,"" Mayer's academic mentor told him, but the young psychologist knew better: he'd taken one on as a patient, a 28-year-old woman whose ""host"" (original) personality, Toby, shared her overweight body with several other full-blown personalities, among them five-year-old Beth, the brilliant adult Anna, and--most startling--the ""Dark Ones,"" a trio of self-proclaimed angels. Stunned by Toby's condition, Mayer researched the scant literature on multiples--neatly summarized here--and devised several techniques, most based on hypnosis, to help Toby. Meanwhile, through contact with the drug-treatment center Odyssey House, he began to receive referrals of other, addicted, multiples, whose cases he here interweaves with Toby's. With persistence, patience, and humor, Mayer finally integrated Toby as, one by one, in a kind of self-sacrificial suicide, her personalities agreed to merge; today, Toby is healthy, and Mayer--convinced that multiple personality is much more prevalent than generally recognized and is always a protective response to childhood abuse--continues to treat multiples and to lobby among his colleagues for increased attention to the disorder. Mayer's humility and growing sense of wonder in the face of the mystery of multiple personality is the humane tie that binds his engrossing book. Full of fascinating cases, rich in information and theory, his memoir is an excellent introduction to anyone interested in learning about this most astonishing of emotional disorders.