First-time author Ginsburg probes the strange case of Audrey Marie Hilley, an Alabama housewife who poisoned her husband and attempted to poison her daughter. The ""Black Widow"" fled arrest, melting into the dull fabric of small-town New Hampshire--until she attracted attention by ""dying"" and coming back as her own twin sister. As a teen-ager in Anniston, Ala., Audrey Marie Hilley had it all. Pretty, preternaturally poised for such a small town, she had her pick of boyfriends, settling on quiet Frank Hilley. As years passed, there were hints of trouble--Marie's greed, an affair with a rich businessman. Daughter Carole started rebelling (vain Marie feared her boyish daughter was a lesbian). Suddenly, Frank got sick with mysterious stomach pains. His condition plummeted, and on the eve of his death he admitted to his sister that Marie had been giving him shots for ""nausea."" After his death, Marie's behavior got outfight strange--she harassed the police department about ominous calls and amassed debts all over town. Then Carole got sick, and Marie's older son Michael grew suspicious (he and his wife had both become ill while visiting). Going on a tip from Michael, a young doctor determined that Carole was suffering from arsenic poisoning. Marie was arrested, but while authorities exhumed Frank's body, she jumped bail--vanishing for three years. Aided by an adoring misfit who became her husband, the chameleonlike murderess hid away in tiny Marlow, N.H., establishing herself as a crack secretary at Central Screw in Keene. The F.B.I. caught her only when alarmed co-workers reported Marie's bizarre staging of her own death. Despite a tendency to repetition that makes the concluding trial and epilogue (Hilley died during a 1987 escape attempt) drag a bit, Ginsburg does a bang-up investigative job overall, producing an absorbing page-turner out of this chilling case.