Seventh in a series set in mid-18th-century London and featuring the sleuthing exploits of inventor-statesman Benjamin Franklin as narrated, written, and sketched by his devoted, illegitimate, 15-year-old son Nick (Murder by the Waters, 1995, etc.). Franklin has been asked by blind Chief Magistrate John Fielding for help in solving the murders of two young women found weeks apart in central London, stabbed to death, their hearts cut out. The first was Tuesday Marrowbone, a prostitute; the second, Hester Ward, the wayward niece of Lord Bathurst, was unloved by her uncle but adored by Tom Elstree, her rejected suitor. The killings, and the cruel pranks of the so-called Dionysus Club, are written up in the London Courant by embittered Jack Scratch, nÇ Pyecroft, once of Oxford University, as were Elstree and the Club's swaggering leader Charles Ravenden, Earl of Chalton. As Franklin and Nick realize that all their investigations lead to Ravenden, he appears to challenge their pursuit with invitations to his London house and to the strange, carnally obsessed structures and caves at Chalton, his country estate. The murder of Jack Scratch; the visit of a guilt-racked Elstree; a trip to Oxford to scrutinize past records; and, once again, a brazen invitation from Ravenden to come to Chalton--all bring about a rousing denouement, its drama heightened by a nightmarish storm. Not too much puzzle in the puzzle here, but Nick grows ever more engaging, and the masterful London scene, pulsing with vitality and crammed with everyday horrors, provides an easy-to- take history lesson in a first-class entertainment.