He grew up in West Covina, California, outside of Los Angeles and attended Occidental College in Los Angeles where he majored in Political Science. During World War II, he used his position as a staff officer in the German Army to employ and protect Jews in the Vilna Ghetto.

Karl Plagge was tried before an Allied de-nazification court in 1947, which accepted his plea to be classified as a 'fellow traveler' of the Nazi Party, whose rescue activities were undertaken for humanitarian reasons, rather than overt opposition to Nazism. Plagge and his former subordinates told the court about his efforts to help Jewish forced laborers; Plagge's lawyer asked for him to be classified as a fellow traveler rather than an active Nazi.After graduating, he married Anke Madsen, but the couple had to live with his mother due to their finances. Michael Good has appeared on C-SPAN, as a speaker in Israel, and in Germany and in schools, libraries, churches and synagogues across the United States. Some of the men were genuine workers, but Plagge also took in hairdressers, academics, kitchen staff and the elderly. When war broke out in September 1939, Plagge, who by this time was an educated man, was drafted by the Wehrmacht, given the rank of Major, and placed in charge of a military motor-vehicle repair station in Vilna.

On 27 March 1944, while Plagge was away on home leave in Germany, the SS carried out a Kinderaktion ("Children Operation"): they entered the camp, rounded up about 250 children and elderly Jews, and took them to Ponary for execution. A few Jews hid in the ruins of the ghetto; arguing that he needed more workers, Plagge brought 100 arrested Jews into HKP.

Following archaeological work done at the HKP 562 site in 2017, a documentary about Plagge and the camp, The Good Nazi, premiered in Vilnius the following year. Former prisoners of HKP 562 in a displaced person camp in Ludwigsburg told Maria Eichamueller [ who? Major (Karl) Plagge was responsible for saving Jewish and Polish people during WWII, including the author's mother. Because Plagge had no descendants, the president of the Technische Universität Darmstadt accepted the award on his behalf.

In September 1943, rumor spread that many of the Jews in the Vilnius ghetto were to be taken by the SS regardless if they had working papers. On March 27, while Plagge was away on home leave, the SS entered the camp and performed a ”kinder action.This expanded edition features new photographs and a new epilogue on the impact of the discovery of Karl Plagge―especially the story of 83-year-old Alfons von Deschwanden, who, after fifty years of silence, came forward as a veteran of Plagge’s unit. Moreover, it takes perhaps a bit of goodwill, occasionally a good idea, and dedication to the task at hand. In this gripping, emotional work, Good explores the life and legacy of a mysterious German officer who secretly defied his government to save Lithuanian Jews during the Holocaust. In this fascinating book, the author, who married a lady of Italian descent, expresses the wonder he used to feel, that at the yearly picnic of his wife's family, there would be crowds of relations, whereas in the case of his parents' family, he could only view photographs of relatives who were all dead. The rest of Vilna's Jews were either executed immediately at Ponary or sent to concentration camps in Nazi-occupied Europe.