Marinette’s class is headed to New York, the city of superheroes, for French-American Friendship Week. The whole class is there...except Adrien, whose father refuses to let him go!

On school break, Marinette heads to Shanghai to meet Adrien. But after arriving, Marinette loses all her stuff, including the Miraculous that allows her to turn into Ladybug!

Miraculous holders from another world appear in Paris. They come from a parallel universe where everything is reversed: the holders of Ladybug and Black Cat Miraculouses, Shadybug and Claw Noir, are the bad guys, and the holder of the Butterfly Miraculous, Hesperia, is a superhero. Ladybug and Cat Noir will have to help Hesperia counter the attacks of their evil doubles and prevent them from seizing the Butterfly's Miraculous. Can our heroes also help Hesperia make Shadybug and Claw Noir better people?

To save the future from a terrible fate, Marinette becomes Chronobug and teams up with Bunnyx to defeat a mysterious opponent who travels through time. Who is this new supervillain, and why are they obsessed with exposing Marinette's secret superhero identity? Marinette's only hope is to defeat her new opponent to prevent the end of Ladybug and time itself!