|Ulrich Tukur||Kurt Gerstein|
|Mathieu Kassovitz||Riccardo Fontana|
|Michel Duchaussoy||The Cardinal|
|Ion Caramitru||Count Fontana|
|Marcel Iures||The Pope|
|Friedrich von Thun||Father Gerstein|
|Antje Schmidt||Mrs. Gerstein|
Nazi officer Kurt Gerstein, a chemist by training, is assigned to develop a disinfectant to purify water for the German army, but soon discovers that his invention, Zyklon B, is being used to exterminate imprisoned Jews. Horrified, he approaches a number of diplomatic figures with his story, but only Riccardo Fontana, a priest, takes him seriously. Fontana returns to the Vatican but is informed by his superiors that they have more pressing concerns.