In Prudhoe Bay, a network of ice roads in the tundra crisscross river systems and open ocean to connect America's booming North Slope oil fields to dry land. Every winter, truckers have less than three months to shuttle critical supplies over the ice. The only problem is there's just one way to get to this remote location: 400 miles of ice-covered, mountainous terrain known as the Dalton Highway. It is the most dangerous road in North America.