During the course of the Second World War, the Allies mounted a series of attempts to prevent Germany from manufacturing heavy water utilising hydroelectric plants in occupied Norway. These efforts comprised a mix of bomber and Commando raids. The overall aim was to stop Nazi Germany building a nuclear bomb. In fact, Hitler was never as close as the Allies thought, but the idea that his regime could construct and deploy such a device was the ultimate doomsday scenario, one that would have tilted the balance in favour of the Nazis. The mere threat might have been sufficient to force a negotiated peace with the perception of a Nazi bomb hanging over the world like a nuclear-powered sword of Damocles. Production, and therefore the Allied target, centred on the Vemork Power Station standing by the Rjukan Waterfall at Telemark. A series of daring raids – Operations Grouse, Freshman and Gunnerside – neutralised the plant’s capacity. In Operation Freshman, every single glider-borne paratrooper was either captured or killed. In February 1943, a force of SOE-trained Norwegian Commandos succeeded in sabotaging the plant’s production capacity. Further manufacturing effort was abandoned, and the Nazis attempted to spirit away the heavy water they had on the ferry SF Hydro. The Norwegians managed to sink the vessel in the deep waters of Lake Tinn. Using primary source material and published on the 80th anniversary of the sinking of the Hydro, The Heavy Water War tells a story of extraordinary courage and endurance. The stakes in any special forces raid in history have never been higher.