Donald Goines
Swamp Man
https://g.co/kgs/o7hn4
I read this when I was like 9 in one sitting at my local library. I had no idea there were such forms of entertainment.
Besides the shock factor of the above, reading about Zen changed my whole approach to life also. No particular book because it's only supposed to take one instant of understanding to become enlightened.
"Don't think. FEEEEEEEEL! It's like a finger pointing away to the moon. Do not concentrate on the finger or you will miss all of the heavenly glory"