Harvard Square's Carlotta Carlyle--our favorite six-foot, red- haired, ex-cop, blues-and-volleyball-playing, cab-driving p.i.--is drawn into a big-money case by a client with an outrageous manuscript of uncertain origins. Having claimed relationship to the powerful Cameron family, Carlotta's client turns out to be the psychiatrist lover of elegant Tessa Cameron, widowed mother to politician Garnet, institutionalized Beryl, and long-dead Thea. Later, he turns up murdered. The manuscript? Could it be the work of Thea, once a literary and sexual prodigy? If so, is Thea still alive and writing? And if she is, who's buried in Thea's grave? And who's using some mysterious scraps of prose to blackmail Garnet, who might have a shot at the governorship if he can just get his semi-estranged wife Marissa under control? But then Marissa is- -isn't she?--kidnapped. Barnes neglects several characters from the excellent series saga who were last represented in 1995's Hardware- -``little sister'' Paolina is at summer camp, and sexy Sam Gianelli in Palm Beach--but devoted cop Mooney is, with his official connections, a great help in grappling with this complicated and compelling case. Carlotta's seventh outing turns melodramatic and ultimately derivative during its payoff pages. Loyal fans will decide whether the author's proven flair for characterization makes it worth the read-time.