Two years ago, Sam Decker climbed into the giant robot Longbow, pulled out the general's frozen son and fired the shot that saved Washington from an alien attack. That same night his best friend died beside him, and Sam walked away, swearing he would never fire Longbow in battle again. Now Grant Holloway is the country's hero for Sam's shot, and Sam hauls shells on his base as the deserter everyone despises. When Grant picks Sam's little sister Tess to ride beside him into the next battle, Sam enters the public trials for her seat, knowing Grant will freeze again and get her killed. The aliens are coming back, and the only man who can make the shot is the one nobody will let near the trigger.
