The Shadow of Theale — Frances Cowen

A three-week "working vacation" at Theale House seemed a pleasant way to spend a holiday. Shortly after her arrival, however, Ruth Hilton realized that beneath a facade of quiet elegance, the peaceful seaside estate pulsed with a malignant evil....

What was the secret of the mute, half-witted retainer who tried desperately to communicate by means of pictures drawn on the family crypt? Why did fourteen-year-old Theo wake screaming in the night? Slowly but surely the events surrounding the disappearance of Lady Theale reached out to cast a pall of darkness about Ruth as she struggled to save her young charge - and herself - from the shadow of Theale.