Karl Marthinsen (1896-1945) was a fanatical national socialist. As Norway's chief-of-police, he was the most important and efficient collaborator under the German occupation in World War II. The Norwegian director Benedicte Maria Orvung was 30 years old when she learned for the first time that this man was her grandfather's brother – her great-uncle. She was in the middle of her film studies in Sweden and happened to come across a newspaper article about him. Her family never spoke a word about Karl Marthinson, who was killed by a resistance group in 1945. Decades later his grandniece tries to throw some light onto this dark family secret. With the meticulousness of a detective she ploughs through archives, questions historians, family members and contemporary witnesses. For many of the people she meets, this is a painful process. Because while Benedicte Orvung's work is important remembrance work for some, there are others who were made to suffer under her great-uncle's persecution and torture who will never be able to forget Karl Marthinson.