In the dark waters of the North Atlantic, the great passenger liner, R.M.S. Titanic, came to a violent and mysterious end. Each of her passengers unwitting players in a harrowing drama. The builder who would pronounce her dead. The brave men who refused to let her die. Thousands of people who struggled for their lives. Now for the first time, a prominent Titanic historian will retell her tragic tale from the ship's actual decks. Haunting locations will take us back to pivotal moments during the epic disaster. Newly discovered artifacts are helping to piece together Titanic's untold stories. It's a moment in history we'll still striving to understand, a part of our past impossible to forget. On the French research vessel Nadir, a countdown begins. The crew prepares for an unprecedented dive to one of the greatest shipwrecks in history, R.M.S. Titanic. On Nadir's fantail, a prototype submersible, Nautile, is run through a final series of systems checks. She is one of a few submersibles able to dive more than twelve thousand feet to reach Titantic.