Loren D. Estleman published his first Sherlock Holmes novel, Sherlock Holmes vs. Dracula, or The Adventure of the Sanguinary Count, in 1978, and it has rarely been out of print; 1979’s Dr. Jekyll and Mr. Holmes pops up nearly as frequently. “Sons of Moriarty,” a full-length novella pitting Holmes against the Mafia, appears here for the first time.