GHOST GIRL: The Story of a Child Who Refused to Talk by Torey L. Hayden (Little, Brown: $19.95; 296 pp.) When psychologist Torey Hayden finally persuades 7-year-old Jadie--an elective mute and the "ghost girl" of the title--to speak, her speech only proves more enigmatic than her silence. Why does she walk perpetually hunched over? "To keep my insides from falling out." Why does she draw large black crosses surrounded by circles? "Because X marks the spot." When similar markings are discovered carved in her sister's skin, an investigation proceeds which reveals that her parents have involved her in a bizarre satanic cult. Hayden recounts this amazing story in artless prose, but the style is a sort of blessing, for it gives what could have been a slick, voyeuristic expose the feel of an empathic, homespun tale.