A Duchess's Secret

In 'A Duchess's Secret', a young novelist is in the process of serialising a racy novel in the Fleet Street Magazine. It tells the story of a Duchess who murders her husband by giving him cheap sherry, in the knowledge that his constitution will not stand such rough liquor. The author is surprised to find a mysterious advertisement in the personal column of The Times which addresses the author of the sherry story and exhorts him to contact a certain firm of solicitors. On making enquiries, the author is invited to a remote stately home to stay with a genuine mysterious duchess who also harbours a guilty secret.