In 1939 Franklin D Roosevelt received a letter from Albert Einstein, warning him that the Nazis might be developing nuclear weapons. America has to act fast.
What follows is the creation of a secret city in the rural area of Oak Ridge, Tennessee. Around 75,000 people moved to the secret city during the World War Two, and the first atomic bomb was developed in just 28 months.
Don Wildman is joined by historian, Ray Smith, to find out how it was possible, and to hear about the experiences of the people who worked at Oak Ridge, most of whom didn't know what they were creating.