Nothing, no amount of training, could have prepared a small group of soldiers from the Durham Light Infantry for what they discovered on 18 April 1945, less than a month before the end of World War II in Europe.

Of the fifty-five million killed during the war, over ten per cent were murdered civilians. A majority of these were Jewish, although there were a significant number of political deaths, and killings of innocent civilians and minorities. This book is about how the world came to hear about these murders in what later came to be called the Holocaust-the collective extermination of...