The Face At the Window — Willo Davis Roberts

All she wanted was to be left alone. When Grace Huntington was discharged from the hospital after a long illness, she looked forward to the peace and solitude of her comfortable house in the country. Except for the neighboring family, there would be no unexpected visitors. Her privacy would be complete. But then her neighbors were murdered, and Grace was faced with a kind of isolation she hadn't bargained for. Because the only visitors she could expect now was a killer on the loose!