When I was younger I read many books about slavery in an effort to understand how such a thing could be. The more I read, the more depressed I became, so I stopped. I realized there was no sane answer to the inhumanity. It was bullying on a large scale. Furthermore, when I found that it was wide-spread throughout the world, then I knew there would never be a solution.
I still prefer science fiction. At least there is some hope for a better future. I enjoy mystery novels too. Robert Parker is one of my favourite authors in that genre.