When brilliant, altruistic Lunella Lafayette accidentally brings a dinosaur to the Lower East Side, she finally has the brawn to match her brains and protect her community.
When Lunella runs the rink for a night, she agrees to Casey's get-rich-quick scheme, which threatens Moon Girl’s reputation and her family's beloved business.
When Lunella loses a game of chess against a supercomputer, her obsession with winning drives the frustrated computer to program every device in the school to attack her.
When Devil Dinosaur gets jealous of sharing Lunella with her class hamster and accidentally sets the animal free, he must search New York City to bring the furry friend home.
Lunella tries to overcome her awkwardness about fitting in at a slumber party by creating a mind-reading device but accidentally switches brains with Devil Dinosaur.
Hoping to help Casey have an epic bat mitzvah, Lunella makes an appearance as Moon Girl, which ultimately brings out the worst in Casey and causes a rift in their friendship.
