The most ambitious race humankind has ever undertaken was masterminded in the shadows by two engineers on opposite sides of the Cold War: Wernher von Braun, a former Nazi officer living in the US, and Sergei Korolev, a Russian rocket designer once jailed for crimes against his country. These two brilliant but controversial rocketeers never met, yet together they reshaped spaceflight and warfare. From Stalin’s brutal gulags and Hitler’s concentration camps to Cape Canaveral and beyond, their simultaneous quests pushed science--and human ingenuity--to the breaking point. Von Braun became an American hero, recognized the world over, while Korolev toiled in obscurity. But as each of these men altered human history, they were eclipsed by their troubled pasts, living out their lives in the shadow of the same moon that drove them to such astonishing feats of scientific achievement.