This book takes you inside the world of the FBI’s special unit that studies the behavior of dangerous criminals. John Douglas, a top agent, explains how he spent years talking to prisoners to understand their thoughts and motives. By learning these secrets, he created a new way to help the police solve mysteries and protect the public. It is a serious and true story about how smart thinking and careful observation can help catch people who break the law. It shows that being a detective is about using your mind as much as your courage.