The story begins in 1882, when Friedrich Nietzsche's beautiful and mysterious former lover convinces the famous Viennese physician and mentor to Sigmund Freud, Joseph Breuer, to cure Nietzsche of his "despair" so that the world will not be deprived of the "most important philosopher of the next 100 years." Breuer is known throughout Europe for his use of hypnosis and the "talking treatment" that have been successful in the treatment of hysteria.

Since Nietzsche is skeptical of what Breuer can do for him, Breuer offers the challenge that they might help each other. Through subterfuge, Breuer convinces Nietzsche to remain for 1 month in the Lauzon Clinic. Their bargain: Breuer agrees to treat Nietzsche for his chronic migraine headaches, if Nietzsche, the great philosopher, will listen to and cure Breuer of his own despair. What follows is a brilliant tour de force in which the two men engage in daily discussion, bantering, and intrigue, much like a chess game, jockeying for position, as both men are transformed in unpredictable and astonishing ways.