Why do we harm ourselves out of resentment towards others? A prominent psychology expert sheds light on this universal human emotion. Have you ever acted foolishly, dangerously, or self-destructively just to get back at someone else? Most of us probably have. In this book, Simon McCarthy-Jones draws on psychology, current affairs, literature, and genetics to reveal – whether we admit it or not – the inherent side of resentment in the human psyche. What is that hidden aspect that makes one secretly wish for a friend's failure? And did Americans elect Trump merely out of spite for Hillary Clinton? There is also a vast number of stories about harmful behavior: in stores, over short fences between neighbors, through divorces caused by malicious instigation, corrupt business practices, political intrigues, and even terrorism based on a "scorched earth" policy. Yet, there is a message of hope; it is the bright side of our dark side, for resentment can push us forward. Hence, Simon offers a new perspective on this concept by highlighting the benefits of resentment as a tool for social equality, a means of rebellion, a source of freedom, and a crucial weapon in our daily arsenal.