Washington D.C. is headquarters for one of the most powerful governments in the world, as well as some of the nation's deepest secrets. The decisions made here echo around the world, so while the seat of power rests above these streets, our nation's security depends on what happens underneath them. From top secret, high tech superbunkers to the underbelly of Capitol Mall, we'll delve into DC's subterranean defenses. Don will discover how the US prepares for the worst...from the ravages of disease to nuclear catastrophe.