Three maids have already been killed on Newport, R.I.'s picturesque Cliff Walk during the summer of 1895 when Rosalind Sinclair's body is found in the same spot. But Rosalind isn't like the other victims. Though she's dressed as a maid, she's the daughter of one of the leading summer families, flirtatious, sharp- tongued--and pregnant. The police, anxious to protect the town's Four Hundred (the elite of the social register), want the killer to be a lower-class servant; but Annie McKenna, the maid at Belle Mer mansion, who heard one of the guests mutter ``That's three'' on the night of the last murder, makes the case more complicated for maverick detective Matt Devlin and his longtime friend Brooke Cassidy of Belle Mer. A fifth killing goads Matt to arrest Brooke's uncle, Henry Olmstead, a gentle drinker who grows the American Beauty roses that have been found on each of the corpses. When Uncle Henry provides an alibi, Matt's dismissed from the force, and his fawning successor, detective William Tripp, promptly arrests a gardener who's obviously just as innocent. Can Matt and Brooke pick out the killer from among the distinguished but indistinguishable suspects before Brooke's summer season comes to a premature end? Rich in social period detail, poor in mystery and detection: a first mystery (Kruger writes romances under the pseudonym Mary Kingsley) for Wharton-starved readers whose noses will wrinkle pleasurably in response to the judgment of Brooke's aunt: ``To identify a dead body is just not done.'' A sequel promises to follow the debutante detective and her bridegroom to New York.