A Scanner Darkly, by Philip K. Dick

An undercover cop’s identity falls apart, as he collapses into the world of a psychotic drug called Substance D. This book will make you feel like you’re the one on drugs. It is cerebral, confusing and like a (well-written) bad trip. And none of those are criticisms. I enjoyed every minute of feeling like my own brain was the one coming apart, and it was with a great feeling of relief that I finished the book and returned to the (relatively) sane real world–a good sign of an absorbing and excellent book as far as I’m concerned.