Gordon Corrigan recounts the story of the 1943 attack on a German hydroelectrics factory in Norway, aimed at thwarting Hitler's plans to build an atomic bomb. The Germans had been carrying out research into harnessing nuclear fission to create a weapon since 1939, and the conquest of Belgium and France had provided them with the materials they needed. The Norwegian plant was producing the 'heavy water' essential to the generation of nuclear power and, once it was in German hands, its resources were diverted to the atomic weapons programme