Autumn of Deception — Maureen Stephenson

To escape seduction by her employer's son, Charles, -- an officer recently returned from the battle of Waterloo, Mary Dordon, governess to his step-sisters, is forced to return home. At first Mary is happy to be back in the sheltered environment of her home. Then she discovers that two local girls have recently been murdered -- both in bizarre circumstances. At the home of the local squire, to her astonishment, she meets Charles, and a few days later one of the mill hands is found strangled. Who is the insane killer in their midst?