I'm fairly certain that Fred Saberhagen was the first author to portray Count Dracula in a positive light, though he was soon followed by a host of others - a flood even - making vampires into sympathetic protagonists. The next may have been Susan Rice, actually, but I digress. I'm also certain that there have been many who have piggybacked upon the Sherlock Holmes mythos over the years, but Douglas may have been one of the first of the late twentieth century to do so, at least in novel form. She, at least, takes a road less traveled, yet similar to Saberhagen's in telling the tales from the point of view of Penelope Huxleigh, Irene Adler's closest confidante.
In Good Night, Mr. Holmes, we get the ladies' perspective on the tag end of the affair from A Study in Scarlet, and then the entirety of A Scandal in Bohemia, which turns out to be far less scandalous than Sir Doyle describes in his reportage. While Miss Adler does not have nearly the powers of observation we find in Mr. Holmes, she is possessed of an intellect and tenacity that serves her quite well in unraveling such small mysteries as she encounters in her travels, such as deducing the identity of the assassin who is slowly poisoning the King of Bohemia, with whose son she is carrying on a mostly innocent affair.
This tale never really rises to the level of intellectual puzzle we find in Doyle's tales, but it's an entertaining new set of eyes, exploring some lesser known figures of Holmes' times. Pick it up at your local library and enjoy an evening or two of innocent pleasure.