Latest in Birmingham's infatuations with other peoples' lives (Shades of Fortune, 1989, etc.)--here in another of his popular tales of Manhattan mensch on the move, with shaky pasts and glittery presents, their women and their well-kept secrets. This time, the death of a famous retail magnate turns out to have been murder, and it's his daughter who'll save both the endangered business and her own self-esteem as her father's past steams open. Silas Tarkington (nÇ Solomon Tarcher), founder and owner of Tarkington's--a Fifth Avenue emporium for the super-rich/super- chic--is found floating in his Long Island mansion's swimming pool. But Silas, it seems, was in perfect health--and why did second wife Consuela, who found the body, call a doctor friend a half-hour away instead of 911? Meanwhile, Silas's daughter Miranda, always discouraged by her father from a career in the store, accepts with pleasure the invitation of Silas's right-hand man, handsome Tommy Bonham, to be a partner in administering Tarkington's. Silas' son by his first wife, however, is not mentioned in the will, and neither is Moses Minskoff, a gross chewer of dead cigars, telephone glued-to-ear--a combo of Bugsy Siegel and Fibber Fox, given to toss off wonders like ``entre vous'' and ``tempo fugit, as the fella says.'' This Birmingham cartoon, broad as a meat axe, has had a lot to do with the rise of Silas Tarkington. Now, out of the mists of the past, arise: ancient mother Rose and sister Simma, as well as a mysterious lady in a West End Avenue brownstone, her hand out for a monthly payment personally delivered by Silas. While Miranda suffers and wonders about Dad's women in and out of wedlock, a nice journalist begins to help Miranda snoop--successfully. An agreeable enough mystery enlivened by Birmingham's sense of intimacy with the scene. The author's following--carriage-to-subway trade--is a given.