Discusses why Pluto is not considered a planet anymore.

Describes Pluto, which was officially designated a dwarf planet in 2006.

When Stink discovers that Pluto has been downgraded from a planet to a dwarf planet, he launches a campaign in his classroom to restore its status to that of a full-fledged member of the solar system.

"Hot diggity dog! Meet Pluto! The runt of a litter of eight planets. Pluto may not be the biggest or fastest planet to revolve around the Sun, but it has a unique story to tell. From the tale of how it was found by humans to its naming as a dwarf planet, it's Pluto's turn to take the spotlight and properly re-introduce itself."--Publisher marketing.

Infuriated by the declaration that Pluto is no longer a planet, President Penguin and his penguins invade Earth and it is up to Ricky and his robot pal to defeat them--with some help from Ricky's cousin Lucy and her pets.