The authors investigate the underlying cultural, psychological, and social forces that have helped to form the concept of retributive justice as it exists today in both the public mind, social media and the legal system. Drawing upon such diverse representations of vengeance as Greek mythology, the plays of Shakespeare, Dante's Inferno, the folklore of the Wild West, the Mafia, and contemporary films, the authors examine the historic and cultural manifestations of the need to inflict punishment on one's enemies. They contend that all acts of vengeance arise from an elemental sense of injustice--conditioned by a desire for equality, justice, and reciprocity. The new introduction extends and highlights the universality of vengeance, its enhancement by modern technologies and builds an even stronger case for it deep biological and animistic roots.