The Nazi evolution from murderous anti-semitism into organised death camps, as documented in this sober piece of historical excavation from Holocaust specialist James Bulgin, is truly shocking in its specificity. An ad-hoc interpretation of party doctrine became an agreed policy of mass shootings on the Eastern Front, before logistical frustrations and concern for the mental health of the executioners prompted a shift to more efficient methods. Almost as distressing as the barbarism itself was the necessary collaboration and complicity of many thousands of locals across Latvia and Lithuania. Harrowing viewing, but it is surely only in better understanding the detail behind the Nazis' mass murders that we can better understand how to ensure it never happens again.