“The discovery of an unpublished manuscript by John H. Watson may well engender in the world of letters as much skepticism as surprise,” Nicholas Meyer wrote in his introduction to The Seven-Per-Cent Solution, his mock Sherlock Holmes adventure that shot up the best seller charts in fall 1974. The book is beautifully done, nicely re-creating the Victorian prose of Arthur Conan Doyle’s stories but bending it to a wacky narrative in which Dr. Watson, fearing Holmes’s cocaine addiction is about to take him over the edge, delivers him to the care of Dr. Sigmund Freud in Vienna. After Holmes throws off his cursed habit, there’s a kidnapping and, wouldn’t you know it, the game is afoot.