The unthinkable has happened! Jedi across the galaxy have been betrayed and murdered by their trusted clone trooper allies. The chancellor has assumed the title of emperor and freedoms once taken for granted have been abolished and suppressed.

Small pockets of rebellion have cropped up throughout the galaxy, but they are hunted and isolated. The best that the protectors of the old republic can hope for now is to survive the brutal onslaught of the empire’s purge. The Clone wars have ended, but the real danger to the galaxy has just revealed itself.

Here is a link to a site that has the core rulebook.
Core rulebook