When Katie Flounders moves to Paris from the United States, the last thing she expects is to become a superhero on the second day of being there. After an akumatized villain targets her, she ends up finding a ladybug patterned box in her room containing a ring that she soon discovers is more than just a piece of jewelry. It's up to Katie to fill the shoes of the previous cat noir that retired ten years ago, and help the new ladybug superhero uncover the identity of the new Shadowmoth. Aiden Agreste feels like he has the perfect life. His parents are known as the old Ladybug and Cat Noir who placed their mantles down ten years ago after the defeat of Shadowmoth, aka his grandfather. He has two younger sisters, twins to be exact, and a great life helping out in his mother's bakery. But he doesn't expect his life to turn upside down when akumas begin appearing again, and for some reason his mother gives him the Ladybug earrings, telling him to go fight the new supervillain and find out the new Shadowmoth's identity. The two are thrown together, but discover that their friendship may lead to something more later. They must learn to trust each other, or Shadowmoth may use that weakness against them.