Plunge into one of the greatest unsolved mysteries of the American Civil War as National Geographic goes in search of the truth about the ill-fated Confederate submarine H.L. Hunley. Discover the desperate ingenuity behind the creation of the first submarine ever to sink an enemy ship in battle. Witness researchers attempts to learn why the Hunley sank and what became of it's crew. Join the mission to raise the primitive hand-powered sub and be there as the Hunley is opened for the first time in more than a century. Considered the ultimate secret weapon by some, a seagoing coffin by others, the legendary warship will break it's 136-year silence at last in Raising the Hunley.