"Daydreamer Jason, 11, has just been [dropped] from his Little League team. Seeking solace at the baseball-card shop, he makes a startling hypothesis: 'Buck McHenry, ' star pitcher [of the Negro Leagues], could be school custodian Mack Henry. Mr. Henry's identity, in doubt through much of the book, provides a mystery, a bittersweet revelation, and a satisfyingly dramatic denouement. The characterizations are pungent, the action (on and off the diamond)...