In the world of books that make people feel uncomfortable because of how real they are, what first comes to mind to me is Gavin de Becker's
The Gift Of Fear.
It is a book about predators and prey. It intimately describes what makes people be violent, how to tell, and how to react to it. It does more than just describe the realities of violence and fear though, it also offers solutions to some of these problems. Some of these solutions seem obvious, because they are problems you
have not wanted to think about. The book
makes you think about things, and sometimes you may be uncomfortable with those thoughts, but they are real. It is an excellent book for anyone interested in human predatory behavior, human prey behavior, violence, fear, and how we react to it.