Vengeance is coming. Monterey Bay, California, has barely survived a brutal attack from the evil invasion forces of Omega, and Cassidy Hart is exhausted. She has lost a friend and gained a new enemy. The militias seem to be weakening, and Omega seems to be getting stronger. In an effort to recruit more troops, Cassidy travels to the desolation of the high mountains to find the mysterious troops of Sky City, and to eliminate a threat that has long been growing just out of the militia's reach. Cassidy is not alone. Old enemies greet her, and the most dangerous person of all just might be the one she trusts the most. The fate of the free world is at stake. The end is coming. The militias - or Omega - will have its revenge.