Today, many of the half-built facilities have been long-forgotten. With previously unreleased film material and exclusive interviews, the fascinating and dramatic story of the Underground Reich is reconstructed when the Nazis leaders still hoped that the miracle weapons they produced would bring Germany final victory.

After securing special permission, a team of highly qualified experts explore the sprawling tunnel systems, finding their way into manmade caverns unseen for decades. The film also documents the horrors faced by forced laborers, compelled to construct the tunnel system under the most inhuman conditions.