Circle of Stones

When she is a young child Elizabeth Keene accompanies her father on an archeological dig in South America. She finds a strange medallion that she takes home with her even though she has strange sensations when she touches it.
Years later when she is an adult and an archeologists she is harassed by a horrifying creature in her dreams who claims that she has something that belongs to him. Soon, her dreams turn into reality when the creature appears in her Waterbury, Connecticut apartment and threatens her life if she doesn't give him the key that he claims belongs to him. The terror intensifies as he follows her to her new home in Kentucky. She enlists the aid of several friends who soon find themselves engrossed in a mystery that threatens the very existence of the humun race.