After a fun-filled summer, Franklin and his friends go back to school. They find that Mr. Owl is out on family business and their substitute is Ms. Koala. Ms. Koala seems very strange to them and Franklin doesn't like her at first when she makes him change seats after goofing off. The class soon learns more about her and comes to accept her "can-do" attitude and ideas of trying new things. Meanwhile, Harriet's best friend Beatrice is going to preschool, but she's still too young to attend. She makes a new friend in Beaver's new little brother, Kit, but not before an unfortunate accident.