Royal Blood by Rhys Bowen.*
Lady Georgiana Rannoch (Georgie to her friends), is again desperate. She has no job, no money, and her sister-in-law Fig has announced that she and Binky (Georgie's brother) will be joining her at Rannoch House in London. Georgie moved to London to avoid living with Fig, and wonders what to do now.
Once again, her relationship to the Queen works in her favour: Georgie is asked to represent the her Family at the wedding of her cousin (and old schoolmate) Princess Maria Theresa in Romania.
Along with a clumsy, inexperienced maid, and an overbearing chaperon, Georgie sets off for Romania. The wedding is to be held at Maria Theresa's ancestral home, a gloomy, isolated castle which was reportedly once inhabited by Vlad the Impaler, complete with a shadowy figure who prowls the halls at night.
The groom is from the Bulgarian royal family, and of course is accompanied by retainers and guards of his own. After dinner one night the Bulgarian Field Marshall Pirin collapses due to an apparent heart attack. Or is the ghostly prowler responsible for his death?
Luckily, the seemingly ubiquitous Darcy O'Mara is with the groom's party, and helps Georgie and her hapless maid to determine what's going on.
The fourth Royal Spyness mystery, despite the grim setting, is as charming as its predecessors. Highly recommended!
*Full disclosure: I received a review copy of the book from the publisher.