One hundred years ago, for Christmas 1920, Chicago bookman Vincent Starrett gave the world "The Unique Hamlet: A Hitherto Unchronicled Adventure of Mr. Sherlock Holmes". Forty-eight years later, for Christmas 1968, August Derleth's Mycroft & Moran publishing house printed Derleth's "The Adventure of the Unique Dickensians" featuring Solar Pons (who is almost but not quite Sherlock Holmes), and a plot line that unmistakably plays off the story of "The...