6. Brainwash: The Secret History of Mind Control by Dominic Streatfeild
This is a history of the government and military's search for a "truth drug" and tactics used for "brainwashing". Really interesting , although not as scary as it sounds since the conclusion is that nothing ever actually was found that would give someone access or control over another person. Basically it's just torture, which makes it very informative given the current world situation.