Frustrated because the rules for her class's Pet Day will not let her take her dog to school, Junie B. Jones considers taking a raccoon, a worm, a dead fish, and other unusual replacements.

When someone takes Justin's karate belt, his friends in Invisible Inc. try to determine a motive as they investigate the mystery.

Junie B is very upset when a boy in her class plans to invite everyone except her to his birthday party, but her grandfather helps her deal with the situation.