This book argues that unforgiveness can be a morally appropriate response to unrepentant wrongdoers and grave injustices. Jennifer M.S. Ang challenges the prevailing emphasis on the benefits of forgiveness, proposing that unforgiveness is sometimes a necessary moral stance, particularly when dealing with absolute evil, systemic neglect, or a lack of justice. The work analyzes forgiveness through three lenses: the release of resentment, the restoration of communal moral relations, and the acceptance of the past. Ang critically examines these concepts through case studies of mass atrocities, including the Nanking Massacre, the Japanese military comfort women system, and the Khmer Rouge genocide, using the Holocaust as a paradigm of absolute evil.

The book presents a rigorous philosophical argument that challenges conventional wisdom on forgiveness. By focusing on cases of mass atrocities and unrepentant wrongdoers, it offers a counterpoint to the often uncritical promotion of forgiveness. The author's examination of the complex interplay between time, justice, and memory provides a nuanced perspective on how victims can achieve closure. The work is likely to be of interest to scholars and readers engaged with ethics, transitional justice, and the philosophy of history.