Sue Grafton's T is for Trespass is one seriously creepy book.
It's not the violence, there is some, but not a lot by today's standards. It's about those who prey on the elderly. getting them to trust them and then abusing them and slowly and systematically robbing them blind. I have elderly parents (fortunately with 3 kids who keep an eye out), but even so the heebee geebee factor is way high. The mind games (and the complete lack of empathy) of the perpatrator just completely unsettled me. My compliments.
I love Grafton's books as I lived in Santa Barbara for 9 years and even though most of the street names are changed she only changes them a little so fans like me know exactly were she's talking about. Cabana Blvd is actually Cabrillo, Capilo is Castillo (there's also Carillo, all major streets - Santa Barbara is tough for lost tourists). Floresta is actually Firgueroa. Far as I can tell where Kinsey lives is completely made up, but with some exceptions, that's about it the rest is completely easy to vizualize which is totally cool.
I listen to the audio books from audible.com and I really like this narrator, more than the previous one with a New England accent (Kinsey lives in S. Calif - decidedly not from New England). My only complaint is that neither of then can pronounce San Luis Obispo (Louis! not Louie - if you can't guess I live there too)