In "The Adventure of Black Peter," Dr. Watson relates:
In this memorable year '95 a curious and incongruous succession of cases had engaged his attention, ranging from his famous investigation of the sudden death of Cardinal Tosca -- an inquiry which was carried out by him at the express desire of his His Holiness the Pope . . .And in The Hound of the Baskervilles, Holmes explains:
". . . I was exceedingly occupied by that little affair of the Vatican cameos, and in my anxiety to oblige the Pope I had lost touch with several interesting English cases."
Both of these cases have inspired numerous pastiches. I myself wrote "The Adventure of the Vatican Cameos," a modern-day short story in which Lynda Teal gets to solve the case on her honeymoon. I expect that to be published as a bonus with my Sebastian McCabe - Jeff Cody novel The Disappearance of Mr. James Phillimore later this year.
Ann Margaret Lewis does a wonderful job of writing pastiches of these two cases plus "The Two Patriarchs" (alluded to in "The Adventure of the Retired Colourman") in her book Murder in the Vatican. I've already highly recommended it in an earlier post. Highlights of the volume include truly wonderful illustrations by Rikki Niehaus and an excellent job of writing about Leo XIII.
Who is your favorite illustrious client of Sherlock Holmes?