Dance with the Devil is a novel written by Dean Koontz under the name Deanna Dwyer.
Description[]
The Devil's Country
Katherine Sellers came to Owlsden in the winter, to be the secretary-companion to Lydia Boland, one of the wealthiest women in the country. The job was an exciting challenge for Katherine, and a needed change from events she'd sooner forget. And her new employer was a charming and gracious lady. If only all of the people of Owlsden and the little mountain village that huddled against the estate for protection were so nice, Katherine's happiness would be assured. However, beneath the charm stirred other emotions, other forces. There was evil in the mountain valley, a brooding evil that worshiped at a dark altar... an altar that had been built for unspeakable sacrifice! And Katherine was marked from the moment she arrived - marked to die!