Dangerous Personalities was written by retired FBI agent, Joe Navarro. He’s written several other books as well - the most popular being What Every Body Is Saying. This book is focused more on applied psychology and indicators to look for in people who you might need to guard against. Sometimes this will be someone who’s an immediate threat and other times it’ll be someone who you’ve known for a while.
Joe gives case studies for some of the most dangerous traits to look for in other people. Some of the traits include psychopathy, sociopathy, narcissism, and paranoia. This book isn’t light reading and should be studied when you’re ready to apply the knowledge you’re taking in. Noticing patterns in people’s speech and behaviors takes dedicated practice, but it’s an important area for you to be able to protect yourself.