Karski & The Lords of Humanity (2015) on Netflix

Plot summary

Jan Karski, a Catholic member of Poland's underground Home Army, works as a courier during World War II. His most prominent mission is to tell the Allied powers about Nazi crimes against the Jews of Europe and to try to stop the Holocaust. To gather what he needs to report, he goes into the Warsaw Ghetto and a transit camp in Nazi-occupied Poland and sees the treatment of Jews there for himself. He then carries his eyewitness account to Britain and the United States, hoping it will move the leaders he calls the Lords of Humanity. The documentary combines animation with archival footage and interviews that Karski recorded after the war, and his own voice narrates the mission.