Oh yes, the details that mean so much that I tend to skim over if I'm so excited to just get started. Sorry about that.

Let's see. I'd say a demon causing most of the problems would be good. Maybe he's gone rogue and has somehow found a way to infiltrate the royal house and is trying to corrupt one of the four princes. Therefore there is slowly becoming chaos for the higher ups and chaos down among the slaves as well.

Would you like modern or medieval? I could do both. As there are supernatural creatures, I'd believe that magic would be a part of the world. So I'm not sure what magic has done concerning their technological advances.