India Black and the Widow of Windsor: A Madam of Espionage Mystery by Carol K. Carr
Black is back-Her Majesty's favorite spy is off to Scotland to save her Majesty. When Queen Victoria attends a seance, the spirit of her departed husband, Prince Albert, insists she spend Christmas at their Scottish home in Balmoral. Prime Minister Disraeli suspects the Scottish nationalists plan to assassinate the Queen - and sends the ever resourceful India and the handsome British spy, French to the Scottish highlands.