This book investigates whether the moral constraints governing the killing of individuals in civilian life apply equally to the conduct of soldiers during wartime. Jeff McMahan, a professor of moral philosophy, utilizes a rigorous analytical framework to challenge the traditional 'just war' theory. He argues that the moral justifications for killing are consistent across all contexts, asserting that the state of war does not provide a unique moral exemption for combatants.

Experts in political philosophy and ethics recognize this work as a significant challenge to the conventional understanding of the moral equality of combatants. Readers frequently note the high level of academic density and the challenging nature of the author's logical arguments.