Shepherd Book belongs to a fairly wide-spread religious order. His story is that he has left his monastery and is travelling as a monk and preacher.
However, not verything about our Shepherd adds up. His knowledge of guns, the criminal world, as well as the activities of Law Enforcement officials. He knows more than a Shepherd should. What is his real story?
We may only ever know one thing about the Shepherd: he has crazy, crazy hair:
Book: "I brought you some supper but if you'd prefer a lecture, I've a few very catchy ones prepped...sin and hellfire... one has lepers."