Most unsettling book you have ever read?

[Bucklion]

The Jungle by Upton Sinclair. Brave New World was kind of creepy too.

 

[Muck]

The Necroscope books by Brian Lumley.

I fought my way through the first one as I am loathe to not finish a book a start....I don't think I made it past the 2nd/3rd chapter in the second one.

*blech*

The Gor books got progressively worse as well.

 

[BB73]

"Man's Search for Meaning", by Viktor Frankl, a concentration camp survivor.