King Leopold's Dream (sometimes Soliloquy) by Mark Twain.
Pamphlet/novelette on the horrors of the Belgian Congo under Leopold - makes nonsense of the 'Gallant little Belgium' slogan.
I read it in my twenties and was knocked out, decided to read it again last year and found to my delight that it was still available (I assume everybody knows about The Book Depository and its 'free postage to anywhere policy)
It is also available for free download HERE
Jim Carroll