It's July 20, 1969. Four days after Apollo 11 thundered skyward from NASA's Kennedy Space Center, astronauts Neil Armstrong and Buzz Aldrin become the first humans to set foot upon the moon, thanks to a marvel of engineering: the lunar module. It's the culmination of years of toil and millions of man-hours of engineering prowess. This is the story of the unsung heroes who built the unconventional flying machines that carried 12 Americans to the moon on six separate missions and made the dream of a generation come true.