Born and raised in the United States, Mildred Harnack was studying for a PhD in Germany when she witnessed the meteoric rise of the Nazi Party. In 1932, together with her husband Arvid Harnack, she promoted the creation of a clandestine group that by 1940 had become the largest anti-Nazi resistance group in Berlin. Mildred recruited new members, helped Jews escape, planned acts of sabotage and, after the outbreak of World War II, she spied for the...