Two treasure hunters in southwest Poland say they have found a hidden tunnel containing a train that may hold rare Nazi gold. It's a claim the local government seems ready to accept, as this is a region where the Nazis were known to hide treasures, from a secret underground super project to a fairy tale castle redesigned as a headquarters for Hitler himself. Witness their attempt to excavate this potential buried treasure, on a mission that will take us into the dark heart of World War II.