What is a major theme in the story?

Besides memories, atrocities of war is a major theme. Jonathan has come to the Ukraine in order to find the woman who saved his grandfather from being killed by the Nazis. Jonathan's grandfather was a Jew and his simple existence made him a target by the Nazis regime that was sent to extricate all Jews from the world. Somehow Jonathan's father escapes both the bombing of his shtetl and the methodical execution of all the Jews who survived the bombing. Nearly fifty years after his death, Jonathan would be given a photograph of his grandfather with a young woman and two people assumed to be her parents. Jonathan is told these people are the people who saved his grandfather from the Nazis. Jonathan wants to find the young woman in the photograph and thank her for her family's generosity.