WHO'S AFRAID?

Sixteen-year-old Billy Jo finds a home and a goal in life, with a little mystery and a hint of romance thrown in. On the bus that takes her from a disagreeable stepmother in Arkansas to her older sister Mary Glynn in Cicero, Illinois, Billy Jo gives her future address to a young man named Dart; he in turn leaves a small metal tool box with her. The box, which Dart says he got from a friend named Greg, turns out to be full of rocks. Billy Jo uses them in a fireplace she builds when she starts helping her brother-in-law Paul restore their old house. Her work wins her praise and personal attention from a handsome young neighbor; respectability-conscious Mary Glynn basks in adult neighbors' approval of the job; Greg lurks about in search of a stolen diamond he'd hidden among the rocks; Billy Jo gets a $10,000 reward for finding the diamond (she'll use it for a down payment to launch a building career); and all strands are neatly tied to end this harmless, lowest-common-denominator piece of girls-magazine fiction,