Arthur and his friends separately find the same metal bobbin but do not know its use, even though it helps them in different ways. Muffy retrieves her toy from a sewer, Francine ends her cat Nemo's fear of water, Brain uses the bobbin as a substitute wheel for his model plane, and even Buster gets the idea to write a story for his favorite TV show. They argue over it and find out that it is Mr. Ratburn's bobbin, and learn what it does at his puppet show. Buster is funny but wants to be good at something else, and Arthur wants to be funny like Buster, resulting in them acting like each other. Francine, Muffy, and Brain try to get them back to normal.