Case #3 for elderly sleuth Margaret Binton of Manhattan's Upper West Side (A Ragged Plot)--whose longtime friend Hannah Jansen is murdered almost before her eyes at Sotheby Parke Bernet: Hannah, you see, was in possession of a rare and extremely valuable coin. So, when the snotty East Side detectives turn out to be of no help, Margaret enlists her coterie of romanticized, oddball friends: Jerry the hustler, Rose the bag-lady, ex-cabbie Roosa. And, in short order, working under Margaret's direction, they identify rich, near-respectable coin dealer Frenos Zarchin as the killer. The plan, then: kidnap Zarchin, incarcerate him, undermine his morale with breakfasts of white bread and Fruit Loops. . . and--voilÃ --a confession and revenge. Thoroughly unbelievable plotting, rather forced charm--but sneaky Zarchin is a zesty villain, and readers with a weakness for geriatric cuteness will find this a genial diversion in the Binton/Barth mold.