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 a young Father Riccardo (Amelie's 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. As the two unlikely allies fight to reveal the truth to the Church and the world, they discover that the fates of a man of conscience committing treason for the sake of humanity and a man of God committing heresy to thwart genocide are ultimately the same.
Costa-Gavras reveals the heroism and deceit surrounding the Vatican's response to the Holocaust with both suspenseful urgency and cool detachment, underscoring the disturbing gray areas of character that tolerated the Nazi atrocities that Gerstein and Riccardo beseech the Vatican to condemn. Without sanctimoniousness, the bitter ironies and hollow victories that are at the heart of Amen. incriminate the Nazis, the Church and ultimately humanity itself.