Amos Ross is a quiet kid. He doesn’t pull pigtails, he always does his homework, and he can’t play marbles. When he brings his grandfather’s championship shooter to show and tell, it catches the eye of the schoolyard marbles champ, Slater, who quickly makes the shooter his own. Julie, a former State champion forced out of the sport by a career-ending thumb injury, convinces Amos that the only way he can reclaim his honor is to beat Slater in the school-wide marbles tournament. As she puts him through a grueling training regimen, Amos learns about his past, confronts his present, and takes control of his future.