After hawkmoth gets defeated everybody grows up, Marinette moved to New York, Adrien stayed in Paris so he could easily see his father who got arrested. Alya and Nino have a child. Chloe lives in New York and is great friends with Marinette. But when an accident happens in Paris they all reunite to fight what they hoped would never happen. This story was written before season 3 so if things don't make sense that's why (such as master fu being in this story) They are like 21 in this story aswell BTW...