James Dawes has written extensively on atrocity and trauma, but he'd never encountered flesh-and-blood perpetrators until he visited Japan in 2008. He went to interview reformed war criminals from the genocidal Sino-Japanese War of the 1930s and 40s, when Japanese forces raped, tortured and killed millions of Chinese. His meetings with the now-elderly men, and the memories they shared with him, left him unnerved and beset by questions. After some years of processing the experience, he's written a wide-ranging meditation on the causes and nature of inhumanity, the stories we tell about it and the very complicated business of bearing witness.