M. E. Braddon 
His Darling Sin 

Grace Perivale is young, beautiful and rich. She and her beloved husband are the center of high society. Until Hector suddenly and unexpectedly dies. Grace is heartbroken and her money and status do nothing to mitigate her desolation. Three years into widowhood, she returns to her London house from wintering in Italy, to discover she is being snubbed by society. Why? Her friend Sue sheds some light on the situation… as unbelievable as it sounds, Grace is touched by scandal. Of course, she denies everything, but who is spreading malicious gossip and why?

She stood alone, with a castle on the Scottish border, round whose turrets the seamews wheeled, and at whose base the German Ocean rolled in menacing grandeur, one of the finest houses in Grosvenor Square, and an income that was described by her friends and the gossiping Press at anything you like between twenty and fifty thousand a year.