Few people have had as much influence on modern psychology as Carl Jung; he has coined terms such as extraversion and introversion, archetypes, anima and animus, shadow, and collective unconscious, among others.
It goes as follows: Man skids into midlife and loses his soul. Man goes looking for soul. After a lot of instructive hardship and adventure — taking place entirely in his head — he finds it again. The book tells the story of Jung trying to face down his own demons as they emerged from the shadows.