When newly-commissioned SS Lieutenant Kurt Gerstein (Ulrich Tukur) witnesses the chemical disinfectant he's helped perfect being used to systematically murder interred Jews, he has no choice but to act. The only sympathetic ear Gerstein is able to find is that of young Father Riccardo (Mathieu Kassovitz), a priest with deep ties to the Vatican. While Riccardo takes on the obstructive Vatican hierarchy, Gerstein must walk a tightrope between documenting and enabling the atrocities his fellow SS officers cold-bloodedly commit.