On a train crossing from Switzerland to Germany, an old man was searched by customs officials. They found 9,000 euros in cash. Their suspicions started a journey back in time, to a hoard of art hidden since the Third Reich. It has reignited passions that seemed long spent. These were not old masters but new - works the Nazis labelled 'degenerate', like the Jews themselves. They tried to wipe out both. The father of the old man on the train was a dealer for the Nazis, selling these works abroad and keeping some for himself. In a two-part special, imagine... follows both his story and those of the families who have been fighting to find their lost art.