As the Red Army pushed west, Nazi units realized their mass shootings across occupied Ukraine and beyond might be discovered, and shifted from hasty burials to deliberate, systematic destruction of evidence. This film follows the French organization Yahad-In Unum as its researchers work in Ukraine's Lviv region, pinpointing execution sites and tracking down elderly eyewitnesses before their testimony is lost for good. Interwoven with that investigation is the story of Rüdiger Schallock, who travels to Lviv to trace what his grandfather Walter, an SS member, actually did there, and what that legacy means for his family now. Historians and researchers explain the escalating methods used to erase the killings, from reburial to incineration of remains, turning what was already mass murder into a second crime of concealment. The film treats this as an underexamined chapter of the war, one still shaping the lives of relatives on both sides, victims' families still searching for remains, and perpetrators' descendants searching for the truth.