"This is heaven, Sorrel Thornhill thought, when she became companion to old Mrs. Vane. No one knew her here or knew about the mysterious death of her husband. And now there was David, Mrs. Vane's son and for the first time in her life Sorrel was truly in love. But the house was not a refuge after all - not after Mrs. Vane was murdered. It was a nightmare repeated, and Sorrel feared that knowledge of the past would tarnish her with guilt. Someone in the house did know, someone who demanded a price for silence that Sorrel would not - could not - pay. She would simply run away, disappear - but there was David and she knew that flight would be an admission of guilt in the eyes of the man she loved."
Used availability for Jane Blackmore's The Dark Between the Stars
September 1981 : USA Mass Market Paperback