Hippocrates' Shadow - David H. Newman, M.D.

I read this in one day. Doctors know many things they don't tell you because of habit, greed, lack of time, and avoidance of conflict. Some examples: cardiac defibrillation rarely works because you're already dead when they do it, screening mammography is a waste of time, and most prescription drugs don't work on those they're prescribed to. A good read.