Fifty years ago, the Dubuyar Empire attacked the Earth with a fleet of advanced starships and battle mecha, not expecting to meet much resistance from the planet with its primitive technology. The resourceful humans salvaged the aliens' wrecked technology, reverse-engineering it so they could produce their own versions. Once the playing field was even, the humans were able to destroy the invaders--but not before the Dubuyar managed to send out a signal. Now, a second alien fleet, larger than the first, is approaching the solar system to begin round two. Outnumbered and overmatched, the fate of the Earth is in the hands of Daphne Willis, who takes the fight to the Dubuyar in the advanced mecha prototype Starbolt. The problem is, Daphne isn't old enough to enlist.