It is 1939. Jan Karski is a brilliant young Polish linguist whose life is one of study, parties and pleasure. Then war breaks out, and suddenly his familiar world is destroyed.
Recruited into the Polish resistance as a secret messenger, Karski must learn to forget his old existence. He will experience bravery and cruelty at their most extreme. And, when he infiltrates the Warsaw ghetto, he is inspired to an act of heroism that could change the course of the war.