No ghost, she. Not Tillie Jean Cassaway either. Seems that the little girl with the long red hair who keeps appearing in the hollow where T.J. drowned three years back--most recently to dreamy, artistic Willy Barbour, 12, and his forthright sister Hilary, 11--is an orphan taken in by lonely ""ole man Craig"" who fosters the ghost story so's he can keep her (and, in the process, confuses the poor girl herself). ""In hill country, there is always mystery""--especially to writers from more mundane places; but this is a blind trail with false clues and hardly a tremble en route.