The SR-71 Blackbird can travel at three times the speed of sound and at heights of 80,000 feet, at the very edge of space. But its greatest legacy is helping maintain peace when the world was on the brink of nuclear war. Even today, this marvel of engineering remains one of the fastest, highest-flying manned planes in the world. This is its remarkable history, through interviews with the men and women who built it and dared to fly it.