It was one of the most audacious exploits of the Norwegian resistance in World War II. On February 19, 1944, three saboteurs crept on board a ferryboat, the Hydro, moored at Lake Tinn in southeast Norway. On board were four dozen barrels bound for Germany and containing deuterium or heavy water, which was vital to Hitler's atomic bomb program. While the boat's crew was happily playing poker, the saboteurs crept into the hold and concealed an improvised time bomb. Next morning, the Hydro exploded as it crossed the middle of the lake, tipping an avalanche of barrels into the depths and killing 18 crew and passengers. Was this daring operation a crucial defeat for Hitler' s nuclear ambitions? An exclusive NOVA salvage expedition sets out to find the Hydro on the bottom of the lake and haul one of the barrels up to the surface. The NOVA team opens up the barrel and a test of its contents helps answer the mysteries surrounding Nazi Germany's race to build the atom bomb. The team also probes Norwegian archives and makes new discoveries: 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. 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.