Karski was a brilliant young diplomat when war broke out in 1939 with Hitler’s invasion of Poland. Taken prisoner by the Soviet Red Army, which had simultaneously invaded from the East, Karski narrowly escaped the subsequent Katyn Forest Massacre. He became a member of the Polish Underground, the most significant resistance movement in occupied Europe, acting as a liaison and courier between the Underground and the Polish government-in-exile. He was twice smuggled into the Warsaw Ghetto, and entered the Nazi’s Izbica transit camp disguised as a guard, witnessing first-hand the horrors of the Holocaust. Karski’s courage and testimony, conveyed in a breathtaking manner in , offer the narrative of one of the world’s greatest eyewitnesses and an inspiration for all of humanity, emboldening each of us to rise to the challenge of standing up against evil and for human rights. This definitive edition—which includes a foreword by Madeleine Albright, a biographical essay by Yale historian Timothy Snyder, an afterword by Zbigniew Brzezinski, previously unpublished photos, notes, further reading, and a glossary—is an apt legacy for this hero of conscience during the most fraught and fragile moment in modern history.