From the back of the book:
Persons of Interest gives the busy GM a toolbox of carefully-crafted implements for fashioning useful patrons and malevolent antagonists to employ or bedevil a party of star-spanning heroes. Within these thirty-three pages you'll find system-neutral tools for identifying NPC motives, particular capabilities and power sources, useful adventure or employment hooks, and distinguishing NPC characteristics.
While Persons of Interest was written for the Stars Without Number role-playing game, the tools in this book are system-neutral, and usable with your own favorite gaming system or sci-fi setting of choice.