Nat Geo's 6-part series "1989," debuts with a dramatic look at a year of revolution around the world. Soviet leader Mikhail Gorbachev's new policies suddenly led to the fall of the Berlin Wall; a government crackdown followed brave protests in Tiananmen Square; and a power shift swept across Eastern Europe. Former Secretary of State James Baker and award-winning journalists provide their stunning, eyewitness accounts of these monumental events in history.