Arthur really wants to enter a song in the Crunch Cereal Jingle Contest, but when he cannot come up with a good idea, he enters a song his sister wrote instead.
Arthur is snubbed by Francine after she hears he said she looked like a marshmallow in her fluffy sweater, but when the two are accidentally locked in the library, they remember why they are such good friends.
Arthur's wrong guess about the identity of the secret admirer sending him valentine messages leads to teasing by the other children, but clues in additional messages allow him to get his due.