In the spring of 1940, as Britain reeled from defeats on all fronts and America seemed frozen in isolation, one fear united the British and American leaders like no other: The Nazis had stolen a march on the Allies toward building the atomic bomb. So began the hunt for Hitler's nuclear weapons. It was to be the most secret war of those wars fought amongst the shadows. The highest stakes. The greatest odds.

Prior to the outbreak of the war the German chemicals conglomerate I. G. Farben - the future manufacturers of Zyklon-B, the gas used in the Nazi concentration camps - had started producing bulk supplies of deuterium oxide-heavy water - at the remote Norwegian plant of Vemork. This was the central target of three separate missions - Operations Grouse, Freshman, and Gunnerside - over the ensuing four years.

Damien Lewis' best seller intercuts the hunt for the scientists, the raw materials, and the plant, with the cloak-and-dagger intelligence game being played in the shadows. This relied in part on Enigma intercepts to guide the SOE's hand. Lewis delves into some of the most extraordinarily inventive and Machiavellian innovations at the SOE, and their related research and training schools, whereby the enemy were tricked, deceived, framed, blackmailed, and double and triple-crossed, all in the name of stopping the Reich from getting the bomb.