From publisher blurb:
Any game world will be composed of a vast array of individuals that are not player characters. These non-player characters make up 99.99+% of the civilized population yet there are only five standard non-player character classes used to represent this bounty of colorful and unique individuals that fill every strata within the game world from the mightiest of emperors to the lowliest of serfs. This supplement offers a quantifiable collection of 16 new NPC classes based loosely from the player character classes. NPC archetypes are also introduced, offering 34 different archetypes spread between all five original NPC classes.
So whether it is a cocky pickpocket the manages to slip out a treasure map or treasured scroll from a wondering player character or a run in with the local bone doctor and his undead minions, there is a plethora of possibilities using these new classes and archetypes.