Impressed with Experiment #458's ability to find anything, Lilo takes him to school for show-and-tell, upsetting Mertle who does not like losing the limelight.
Phineas and Ferb create their own language, and it catches on quickly; Candace is puzzled when she finds everyone speaks a language she does not understand.
Bill realizes that his favorite comic might not be who he claims to be, and Cricket takes on a comic who specializes in insults; Tilly defends Cricket.
As Cricket and Tilly spend time with their grandpa, Nancy tries to find him a job; Bill hoards various items in the hopes of ensuring his family's future.
When Cricket develops an unwanted crush on Gabriella during the Valentine's Dance, it begins to lead to some drama; Cricket teams up with Officer Keys.
The children try to retrieve Nancy's trailer after her old biker gang steals it; the Green family threatens Cricket's success with house-sitting for Remy.
Cricket is determined to avoid going to the dentist and Bill struggles to complete a puzzle; Tilly and Andromeda plan to stay up all night during a sleepover.
Tilly borrows an alien chemical from Gwendolyn Zapp to make Bill's pumpkins larger, but the chemical causes them to transform into body-snatching monsters.
When language teacher Miss Caline Bustier is unexpectedly transformed into an evil villain by the name of Zombizou, Ladybug and Cat Noir must stop her.
Human children go to school during the day while monster children have their lessons at night, and the monster children try to keep their existence a secret.
Merian tries to save Dr. Lullah's poor fish counter from a life of busy work; the kids put on a stage play to warn the mutants of an incoming disaster.
Mabel befriends a Merman that is trapped in the deep end of a public pool, leading her to find his family in the ocean, even if it means their romance will end.
After he freezes in the face of danger, Remy embarks on a journey to become a martial arts warrior who will take action; Cricket's dirt jar goes missing.
Cricket learns how to drive a tractor while Remy searches for his "country grit"; Gramma and Gloria visit a club; Phoenix heads back to Big City for Saxon.