“A horrific photograph of an execution in eastern Europe during the second world war can be seen in Holocaust archives and museums around the world. But who are the killers, who are the victims, who took it – and why?” The date and location given for the photo are misleading, for there were supposedly no Jews left in the identified town at the time, and in fact, no historian has been able to positively identify the victims as Jews, or their tormentors as Nazis. One researcher has devoted years to finding the answers, and all she has discovered is that the Holocaust remains simultaneously one of the most well-documented and murkiest events in human history.