Cora Felton does like her nip of gin after lunch, or even before lunch, but her neighbors in bucolic Bakerhaven, Conn., are all proud of her reputation as the Puzzle Lady, whose photo accompanies the crosswords syndicated throughout the land. When an unknown girl's corpse is found in Bakerhaven Cemetery, Cora has a chance to put her expertise to work on a real-life clue: a scrap of paper with the tantalizing notation ""4) D -- LINE (5)"" found in the stranger's pocket. And here comes the first of many gentle surprises: Cora's niece, Sherry Carter, and police chief Dale Harper, who brings her the puzzling paper, find that she'd much rather analyze more concrete physical evidence--why wasn't the dead girl wearing shoes or socks?--than solve the cruciverbal clues that keep arriving in the mail, or on further corpses. Equally surprisingly, Cora's ideas about publicity create a running battle with the cop who's counting on her for help. Hall, in a striking departure from his Stanley Hastings series (Suspense, 1998, etc.), provides a suitably pastel background for the tale, but the real lure here is the mystery, whose ingenuity takes quite unexpected forms en route to the final unmasking. Heaven for crossword fans, who'll rejoice over the solve-as-you-go puzzle that eventually reveals the killer for readers whose pens are mightier than their reading glasses.