There are people who don't recognize good and bad. They appear normal, even charming, but lack conscience and empathy. They see others as objects to use for their own benefit. They are called psychopaths. They are out there, wandering among us, and there's nothing we can do about it.
Liz Nugent's Lying in Wait is about just such a person. The path to who this person is and what they are willing to do leads the reader on a terrifying maze of twists and turns of shock and second-guessing, and in my case, a little shrieking.