This is on one hand a compendium of all the research that has been made about psychopathy, the footnotes are extensive and it´s easy to go from Lingh to any other author that you´d like to dive more deeply into. On the other hand, it´s a very personal account and reflection about the psychopath in general and psychopaths that the author has met, both in his profession as a psychologist and as a lecturer and teacher. I reminds me a bit about my own binders from the courses I took at university. You get the feeling Lingh wants to share a lifetime of collected knowledge and a huge fascination for these people.
Surprisingly, I find that I´m pretty well read on the subject. I have already encountered most of the authors he mentions, one way or another. Why does one get this fascination for people that are "mad, bad and dangerous to know"? I suppose it´s like being really into World War II documentaries or horror flicks. You´re attracted to what scares you the most. Perhaps the instinct is that knowledge will make it less scary, like trolls that go "poof!" when you look directly at them. I´m not sure it works, though. Which is probably why literature is, has always been, and always will be totally preoccupied with war and scary people.
If you are as fascinated by the subject as I am, I do recommend it. You´ll get through it rather quickly, because it´s a bit of a pageturner. At least, it was for me.