When a dissolute young member of the Upper Ten Thousand is discovered murdered in his bed, surrounded by erotic paraphernalia, Sir Henry Lovejoy summons Sebastian St. Cyr to investigate. As Sebastian begins to question suspects, it becomes apparent the widow of Lord Ashworth, Sebastian's niece, rises to the top of the list. But, Lord Ashworth was not a good person and a lot of other people wanted him dead. Too many people. Meanwhile, a delegation of Russian diplomats, heading by the Tsar's sister and her entourage, including Lady Ivanna Gargarin, arrive in London to negotiate the set-up of post-Napoleonic Europe. This adds another element to the investigation. As Sebastian worries about his niece, more bodies turn up. This is a very well-written series of historical thrillers, written with an eye for detail. I like the characters, who are fully developed. Recommended.