Though only twelve, Bax (short for Johann Sebastian) Barlow tries out for and is awarded last chair in his town's new summer orchestra, and this lightweight mystery centers on the elegant violin and case which his aunt has bought in a small shop in Germany, then switched for Bax's when people started trying to steal it and she became uneasy about traveling with it. But Aunt Daphne's odd disregard for Bax's safety is no better explained than are all the incidents involving bushy-haired prowlers, the orchestra sponsor's suspicious interest in the violin, the conductor's suspicious interest in the case, the instrument's mysterious disappearance and reappearance, and a seemingly menacing hippy's frantic pursuit of Bax in a remote and stormy setting. Despite the Del Fiore marking on the violin, Aunt Daphne's instrument turns out to be a late-19th-century factory imitation, thus not worth such attention; tucked away in the case, however, Bax finally finds some valuable missing Beethoven notebooks. All suspects turn out to be innocent--the hippy a U.S. agent charged with recovering the notebooks, the conductor his friend and helper, the sponsor a potential purchaser of the believed Del Fiore--which makes their cloak-and-dagger machinations all the sillier. However, that won't bother those summer reading club record-breakers, who can dash through the book as rapidly as Bax does through the false leads and slick solution.