Marinette Dupain-Cheng is babysitting a child named Manon when her best friend, Alya Césaire, visits her. Alya tells Marinette that her crush, Adrien Agreste, is having a photoshoot nearby and takes them to see him. Meanwhile, Aurore Beauréal has just lost to her competitor, Mireille Caquet, to be nominated as the next weather forecaster. Mad that she is unpopular, Aurore falls victim to the villainous Hawk Moth and akumatizes into Stormy Weather, a supervillain who controls the weather. When Stormy wreaks havoc in Paris and interrupts the photoshoot, Marinette transforms into her secret superhero persona, Ladybug. At the same time, Adrien transforms into his secret superhero persona, Cat Noir. Together, they work to defeat Stormy, but are oblivious to each other's identities.