In the spring of 1945 the Allies arrested the physicists they believed had worked on the German nuclear programme during the war. Interned in an English country house, their conversations were secretly recorded. MI6's Operation Epsilon sought to determine how close Nazi Germany had come to building an atomic bomb. It was in this remote setting - Farm Hall, near Cambridge - that the German physicists first heard of the bombing ofHiroshima. August 6 1945 was a night that changed the course of history. The terrible weapon unleashed on Japan caused unprecedented destruction and loss of life. That the Allies had such a weapon at their disposal came as a great shock to the German scientists who had worked under the assumption that the Allies knew nothing of nuclear fission. This is the story of the wartime race to develop an atomic bomb, and the genius, guilt, complicity and hubris of Nobel Prize-winning scientists working to create a weapon that would undoubtedly have won the war for the Germans.