Karl plays USA GI John in the German Language film "Saviors in the Night" based on the memories of Marga Spiegel, published in 1965.
The film follows how courageous farmers in southern Munsterland hid Marga, her husband Siegfried and their little daughter Karin from 1943 until 1945, thus saving them from deportation to the extermination camps in the East. They risk their own lives, and, if necessary, even that of their families.