Sherlock Holmes goes still another 15 rounds with Jack the Ripper without getting a clear decision--though dedicated fans will have no trouble piercing the great detective's seemly reserve to identify the latest contender for Jack's identity. This final revelation, inventive and original--though offered without supporting evidence--is the best thing about TV journalist Hanna's first novel, which is remote from Conan Doyle's crisp, vivid writing in its third-person voice, its blurry diction, and its lumbering pace. Despite cameos by Wilde and Shaw and more substantial turns by Lord Spencer Churchill and the fashionably requisite members of the royal family--especially feebleminded Prince Eddy and his Teutonic father--nothing seems to happen (except to the half-dozen prostitutes whose deaths Hanna rehearses with grisly relish) until the final expectant tableau. True-crime Sherlockians can expect a ripping good time right down to the 25 pages of footnotes. Others need not apply.