Marinette Dupain-Cheng is babysitting a child named Manon when her best friend Alya visits her. Alya tells Marinette that her crush, Adrien Agreste, is having a photoshoot nearby and takes them to see him. Meanwhile, Aurore Borell has just lost to her competitor, Mireille Jattée, to become the next weather forecaster. Infuriated, she becomes influenced by the villain Hawk Moth and turns into 'Stormy Weather', a villain who controls the weather. When Stormy wrecks havoc on Paris and interrupts the photoshoot, Marinette transforms into her secret super-hero persona, 'Ladybug'. At the same time, Adrien transforms into his secret super-hero persona, 'Cat Noir'. Together, they work to defeat Stormy.