The Winter Fortress

The Epic Mission to Sabotage Hitler's Atomic Bomb,
by Neal Bascomb.
In 1942 the Nazis were plotting to build an atomic bomb. They needed one special ingredient, heavy water, produced in the castle fortress at Norway's Vemork, set on a precipitous gorge in one of the most inhospitable places on Earth. With never before seen diaries and letters of the saboteurs, this arresting chronicle tells of how the Allies learned of the importance of this plant, and the "impossible" mission that came about through incredible odds to destroy it.
Now in Paperback, 378pp. 2016