Witness aviators challenging barriers as the world's fastest aircraft, from the X-1 to the futuristic SR-71, push the limits of speed. Follow their quest to make supersonic speed practical and hypersonic speeds possible. This is a story of the courage and skill it takes to fly faster than the speed of sound. Follow pioneering heroes like Chuck Yeager and Scott Crossfield as they transcend the limits to take their radical aircraft to unthinkable speeds.