Miraculous carriers from a parallel world appear in Paris. Ladybug and Cat Noir seem to be chasing Butterfly, just as Ladybug and Cat Noir usually do... except that for them, everything is reversed. And it's for the wrong reasons that Shadybug and Claw Noir want to take over Hesperia's Miraculous. Can Ladybug and Cat Noir help Hesperia make Shadybug and Claw Noir better people?