In a rolling sea off the coast of South America, a target disappears in a puff of green light. In the Soviet hills of Dushanbe near the Afghanistan border, an otherworldly array of pillars and domes rises into the night. To the two greatest nations on earth, no contest is more urgent than the race to build the first Star Wars missile defense system, and no one knows that more than the two men charged with assessing the Soviets' capabilities: Colonel...