Final Fantasy: The Spirits Within — Dean Wesley Smith

Earth, 2065 A.D.: Destruction and confusion are everywhere. Cities are deserted, the population is decimated, and the few humans who remain struggle to survive against an insidious alien presence that is consuming the very life energy of this wounded world. The presence is spreading across the planet, infecting everything in its path, killing the Earth one life at a time. Only Dr. Aki Ross, a brilliant young woman haunted by dreams of death, may hold the key to saving the world.But her plan is not without its risks, and a rogue general commanding the most technologically sophisticated army in history will storm heaven itself to stop her if he has to. He has plans of his own to stop the alien life force in one decisive stroke...plans that will stab at the very heart of Nature itself unless Aki's quest succeeds.