In rural Montana, a dangerous militia group known as the Diamondbacks is about to cross the line. As a U.S. space shuttle prepares for liftoff, the Diamondbacks seize control of the shuttle's tracking station, and hold the shuttle and its crew at bay. Enter the FBI and two dedicated controllers from the Space Center in Houston. With the countdown under way, mission control must find a way to stop the militants before the shuttle and its crew are lost forever. But as the seconds tick by, the Diamondbacks have a few surprises of their own, and the two sides face off in a battle that could change the course of mankind.