Disaster at Yellowstone — Kendra Campbell

This is the third book in a series of three. This series begins with a volcanic network which possesses humans with a spirit of the hills and turns them into something we would no longer consider human. The story maps the progress of one particularly human and her fight to remain that way while some of her friends and her family have turned against her because they have become possessed. With the help of her true friends, she begins a war against the spirit which destroyed her family and the families of her friends