Twelve-year-old April O'Day's summer has gotten off to a flying start. As the new bat retriever for the Harpoons, her hometown's minor-league team, she's fetching bats and doling out great advice to players and coaches alike. In a word, she's becoming indispensable. But mysterious things are happening at Haney Field, which April and her best friend-and fellow baseball enthusiast-Darren Plummer are determined to uncover. As they quickly learn, this is no ordinary season. In fact, it's a whole new ballgame