It's the last kind of case that San Francisco private investigator John Marshall Tanner would normally accept. But Chandelier Wells comes with a personal referral Tanner cannot refuse. For all her money and fame, Chandelier is scared. Someone is sending anonymous notes: "If you don't stop, you will die " Stop what? She says she doesn't know, and she has no time to find out before beginning the publicity tour for her new book, "Shaloon." Chandelier writes romantic suspense, but she takes on tough issues. "Shaloon" attacks the cosmetics industry, and next year's book, just finished in manuscript, dissects the luxury cruise business. Could the research for her books have made her the kind of enemies who would wish her bodily harm?