After nearly defeating the fifth graders in a game of dodgeball, Bart's class gets into a rumble with the older boys.  Just as Bart is about to fight one of them, he learns they share a scar together.  Through Dr. Hibbert, Bart learns he must go to Comic Book Guy to learn the origins of his scar.  CBG leads him to his old daycare group of friends, which makes Marge rekindle her friendship with their moms.  Eventually Marge remembers whey she left the group in the first place, while poor Homer and Bart are stuck hanging out with the fathers and sons they hate respectively.