Peril at Stone Hall — Jane Corby

THE TOWER ROOM

...held a mystery as impregnable as the walls of the castle.
Skeletal hands appeared at its window. Low sobbing floated from behind its iron door, and a broken voice ceaselessly sang a child's nursery tune.

Dory heard the sounds and saw the shadows move, but the others blamed it on the howling wind and her imagination.

Was she going insane?

Or had she stumbled upon a secret that would keep her forever entombed inside the castle?

When Dorcas Lane, researcher for a historical foundation, was offered a position examining and assessing a collection of Revolutionary war documents belonging to a family at Stone Hall in upper New York State, she accepted with alacrity. For, unknown to her employers, she hoped to be able to unmask an impostor who was preying on them.

A senile old lady obsessed by her son, another member of the older generation locked away in a tower, strange noises emanating from an empty room, and a fence along a cliff which is mysteriously moved--all spell danger to Dorcas as she engages in her desperate quest.