This episode uses captured Nazi documents, expert commentary, combat and archival footage and the recollections of the soldiers who lived through D-Day to tell the story of the most extensive defensive edifice erected since the Great Wall. The video visits the now-quiet coastlines where the remnants of the massive network remain and details the different defenses and weapons that were supposed to make the European coast impregnable. Then, see how the Allied commanders plotted their attack and hear from the soldiers who were charged with making their strategies work.