What is the most disturbing book you have ever read?

https://lemmy.blahaj.zone/post/149526

What is the most disturbing book you have ever read? - Blåhaj Lemmy

Tell me about a book that disturbed, distressed, shocked, traumatized, or unsettled you in any way. Please elaborate on why it does.

In honor of Cormac McCarthy, Blood Meridian is pretty fucked up, I like it better than The Road (although excellent as well) because it's just more verbose.