Freshman Bobby Hill drinks a potion that turns him from a know-it-all teen into a 25-year old man everyone thinks is the school's new assistant baseball coach. Bobby suddenly finds himself running the team, using an expense account and avoiding the coach's man-hungry daughter. "All I wanted was to play baseball," he whines to Wally, another teen who spends more time on the psychiatrist's couch than behind the plate. During the big tournament, Bobby wants to help the losing Zephyrs win, but it's every man (and boy!) for himself as he ducks newspaper reporters, his worried mother, the principal, the coach, and even his teammates.