The Good Nazi tells the story of Major Karl Plagge, a Nazi officer who, during the Holocaust, was commandant of a forced labor camp called "HKP" in Vilnius, Lithuania. In reality, he was sheltering hundreds of Jewish families. By the end, many were saved in hiding places dug into the ground and carved into the walls. Many more were executed by the SS and buried in a mass grave. Today, the former "HKP" is unchanged. A group of scientists arrive to locate the hiding places of those that were saved and identify the mass grave of those who were murdered. A child survivor of the camp and an American physician, whose mother was saved by Major Plagge, join them. The film tracks their three stories and, ultimately, brings to light the unknown tale of a Schindler-type German who listened to his conscience, instead of his superiors.