Those fey, glib, and clever sleuths at Washington's Werner-Bok Library--lovely Crighton, smooth Steve, and retired Yale mastermind Edwin George--are back. . . in a talky, benign mystery that's not quite the charmer that Dewey Decimated (1977) was. This time the crux of the matter is rare-coin collecting--members of a coin club are being shot and robbed--but Goodrum doesn't lecture as suavely on this topic as he does on strictly-library matters. In fact, the best parts here are Mr. George's skeptical inquiries into the new library computerization: the sleuths (two of whom finally cement a romance) use computers in their investigation, finding out just how fallible the machinery is. For librarians and numismatists, then--dandy. Otherwise, just passably cute.