We have always struggled to explain why some people behave in the most evil way imaginable, while others are completely self-sacrificing. Is it possible that - rather than thinking in terms of 'good' and 'evil' - all of us instead lie somewhere on the empathy spectrum, and our position on that spectrum can be affected by both genes and our environments? Why do some people treat others as objects? Why is empathy our most precious resource? And does a lack of it always mean a negative outcome? From the Nazi concentration camps of World War Two to the playgrounds of today, Simon Baron-Cohen examines empathy, cruelty and understanding in this fascinating and challenging new look at what exactly makes our behaviour uniquely human.