The author was a downtown darling 15 years ago, and her Slaves of New York was all the rage for a time. She's been relatively invisible since, however, so news that she has just sold a new novel to St. Martin's, which is describing it as "a Madame Bovary for our time," is noteworthy. It was senior editor Diane Higgins who bought the book, called Peyton Ambrose, for North American rights from agent Betsy Lerner at the Gernert Company, and plans to publish it next fall.