The Psychopath Code [1], by Peter Hintjens. You can download a free legal copy.
Psychopaths and sociopaths are out there: they're about five to ten percent of the population. Once you've had your life intertwined with one, you'll never see the world the same. Know how to identify them and deal with them.
I learned about Peter Hintjens and his book when his death was reported here on Hacker News.