One of the most daring resistance operations of World War II was the 1944 sinking of the Norwegian ferry Hydro, with its cargo of "heavy water" destined for the Nazi's secret atomic bomb project. If the Germans had obtained a large supply, it could have helped their physicists develop nuclear weapons that would have made the Third Reich invincible. Fear of that outcome sparked the Allies to undertake the Manhattan Project, which ultimately produced the first atomic bomb. But was the blowing up of the Hydro a crucial defeat for Hitler's nuclear ambitions? An exclusive NOVA salvage expedition sets out to explore the bottom of a Norwegian lake with a remotely operated vehicle--its goal is to discover the sunken ferry and haul up one of the barrels believed to contain heavy water. Testing the barrel's contents will provide a crucial clue to resolving the riddles surrounding Nazi Germany's push to build the bomb. Hitler's Sunken Secret features gripping first-person interviews with the sole living Norwegian saboteur and survivors who were on board the Hydro when it blew up. Among the NOVA team's startling new discoveries is evidence that a second secret consignment of barrels eluded the saboteurs and made it all the way to Germany, but arrived too late to make a Nazi bomb feasible.