He’s a Bully, Charlie Brown

Charlie Brown offers his own marbles because Rerun came to him upset after Joe Agate tricked him into playing for keeps and took all his grandfather's marbles. Charlie feels responsible for his friend and decides to take action, even though he has never learned to play marbles himself. His determination to help Rerun stems from his character trait of standing up for friends despite his usual lack of confidence.

Snoopy coaches Charlie Brown in marbles while the other children are at camp. Charlie isolates himself to practice under Snoopy's tutelage, learning strategies and techniques for the upcoming confrontation with Joe. Snoopy's coaching gives Charlie the confidence and skills needed to challenge the bully.

Earlier, Rerun tells Charlie Brown about losing his marbles, setting the stage for Charlie's determination to learn.

Joe Agate uses his marble skills to take advantage of beginners at camp. He falsely claims games are "for keeps" when playing against inexperienced kids, allowing him to win their marbles legitimately according to his own rules. His motivation appears to be collecting marbles from others, particularly prized ones like his shooter, rather than genuine competitive play.

On the final day of camp, Charlie Brown challenges Joe at the trading post and exposes his unfair tactics of preying on beginners. The match is intense, with Joe initially winning. However, when it becomes clear Charlie was using borrowed marbles, Snoopy provides spare marbles, forcing a restart. Charlie regains composure and eventually defeats Joe, winning all his marbles including the prized shooter.

Earlier, Charlie isolates himself to practice marbles, building toward this confrontation.

Snoopy provides spare marbles because Charlie Brown was using borrowed marbles from other kids, which could have invalidated his win. The spare marbles allow the match to continue fairly and give Charlie a legitimate second chance. This moment highlights Snoopy's role as a supportive friend who helps level the playing field against Joe's dishonesty.

Peppermint Patty originally stays behind to attend summer school, which disappoints her. However, she later travels to camp because she becomes jealous, fearing that Marcie has a romantic interest in Charlie Brown. She arrives hoping to confront the situation, only to discover Charlie has been absent training to face Joe.

Charlie Brown announces he will return all the marbles to their rightful owners, starting with Rerun who lost his grandfather's marbles to Joe's trickery. He keeps none of the marbles for himself, demonstrating his genuine motivation was to help friends rather than gain possessions. Joe concedes defeat and leaves camp after losing his prized shooter.

When back home, Marcie teasingly tells Peppermint Patty about a Moonlight Walk with Charlie Brown, implying something romantic happened between them. However, she then reveals the reality: Charlie Brown walked into a tree during the evening stroll. This comedic twist plays on the classic Peanuts trope of Charlie Brown's clumsy, unlucky nature ruining potentially romantic moments.

Marcie celebrates Charlie Brown's victory over Joe by kissing him on the cheek. This gesture shows her affection for him and marks a happy moment after the tension of the marble challenge. The kiss also sparks Peppermint Patty's existing jealousy, adding a brief romantic element to the camp's celebratory mood.