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.

I read The Shards by Bret Easton Ellis a few months ago and it had some incredibly grisly passages describing the killer's victims.