The concept of evil is universal, ancient, and ever present today. The biblical book of Genesis clearly defines it when Cain kills his brother Abel out of jealousy. As long as human beings have walked, evil has been close by. This book will recount the deeds of the worst people in history: Genghis Khan. Caligula. Henry VIII. The collective evil of the slave traders. Stalin. Hitler. Mao. The Ayatollah Khomeini. Putin. The Mexican drug cartels. Their...