Spring 1943. World War II is slowly beginning to turn in favor of the Allied forces. But, growing desperate, Hitler hatches plans for a diabolical weapon: a bank of “superguns" housed in a massive underground complex in Nazi-occupied northern France. Together the guns would be able to pump 300 heavy high explosive shells into downtown London every hour—a target 100 miles away. This weapon could spell doom for the Allies. But how can such a massive gun possibly work? Join NOVA as engineers, archeologists, and World War II historians investigate this fearsome weapon. And discover the two audacious missions designed to destroy the seemingly impregnable supergun complex, one of which is led by none other than Joseph Kennedy Jr. Can these hair-raising missions save the Allied forces?