The dying days of World War II. Hitler was in his bunker, unable to accept defeat. But most Nazis knew the game was up. It was time to start hiding evidence of their crimes. A unit of SS officers were instructed to transport boxes to the Salzgammergut lake district in the Austrian Alps. Their destination was one of the most remote and deepest lakes in the region: Lake Toplitz. On 1st May 1945, eyewitnesses still alive today saw the SS Officers throwing the boxes into the lake. Local rumours grew: the boxes were full of stolen gold. It was the biggest bank heist in history.