Combining unique archival footage with animated sequences, Slawomir Grunberg tells the story of Jan Karski, hero of the Polish underground and the first person to reveal to the Western Allied governments the atrocities and mass murders committed by the Nazis in occupied Poland. Karski infiltrated the Warsaw Ghetto and a Nazi transit camp and carried his dreadful eye-witness report of the atrocities to Britain and the US, hoping that it would shake the conscience of the powerful leader or – as he would later call them – the Lords of Humanity.