In 1939, Gustav Kleinmann, a Jewish upholsterer in Vienna, was seized by the Nazis. Along with his teenage son Fritz, he was sent to Buchenwald in Germany. There began an unimaginable ordeal that saw the pair beaten, starved, and forced to build the very concentration camp they were held in. When Gustav was set to be transferred to Auschwitz--a certain death sentence--Fritz refused to leave his side. Throughout the horrors they witnessed and the suffering they endured, there was one constant that kept them alive: the love between father and son.