From the introduction:
In 1748, an English sorcerer named Matthew Whitlock came to the New World to seek a safe haven in which to conduct his arcane researches. While traveling in what is now Maine, he encountered a local tribe and learned that they possessed artifacts of some power. In 1751, he stole some of these artifacts and returned to his cabin to continue his studies. Some months later, he met his death at the hands of a group of trappers, who encountered him while he was conducting an unspeakable ritual in the woods. After burning the sorcerer’s body, the trappers informed a traveling minister of what they had done. Aided by the trappers, the priest burned the sorcerer’s cabin and then sealed up the entrance to the chambers beneath it.
Unfortunately, Whitlock’s sorceries and terrible hatred permitted him to continue to exist after his death as a horrid wraith. This wraith has continued to exist since then, giving the area (known as "The Three Stones") an evil reputation.
This adventure was self-published in 1994 and re-published on the web with minor corrections in 1996.