Because I like this version better than a lot of other versions.
Once upon a time two girls are born to two different parents. One is Bridgette, Princess of the kingdom who long for freedom, especially the freedom to marry her tutor and friend, Felix. The other girl is Marinette, who longs to see the world.
Bridgette learns she is to marrying the king of a nearby country in order to save her kingdom from bankruptcy. The truth is that the royal adviser, Hawkmoth has been stealing from royal mines. He plans to have Bridgette disappear, with him appearing to rescue her. The queen would be so grateful that she would have the princess marry him and he would be king.
Felix takes Bridgette to the city for a day of freedom, when she meets Marinette. The girls discover they are near identical, except for a crown shaped birthmark Bridgette has on her shoulder. The girls part as friends. That night, Bridgette is kidnapped along with her cat Tikki, the kidnappers leaving a letter saying she ran away.
Felix suspects Hawkmoth is behind this and asks Marinette to pretend to be Bridgette. When Marinette appears as Bridgette, Hawkmoth is surprised since he thought she had already been kidnapped. The king from the neighboring country, King Adrien, visits and gets to know Bridgette (Marinette) who find herself falling in love with the King, but is worried what will happen when people find out she is not the princess.
Bridgette escape her kidnappers. Felix follows Hawkmoth to the place where they kept Bridgette but is captured. Bridgette tries to get back into the palace, but the guard refuse her since they think the princess is inside. She is found by Madame Bourgeois and is taken home, since Madame believes she is Marinette.
Hawkmoth discovers Marinette is a fake with a note Bridgette tried to sneak inside using Tikki. Hawkmoth takes Bridgette to the mine when Felix is held, intending to collapse the mine on both of them. He exposes Marinette as a fake and accuses Felix of treason. Marinette is imprisoned. As Marinette tries to escape, she runs into a disguised Adrien who says he believes her. As Bridgette and Felix try to escape, the find some of the rocks are actually geodes, which could help save the kingdom. With help from Marinette's cat Plagg, Bridgette and Felix escape.
Hawkmoth convinces the queen that Bridgette is dead, and that they must marry to save the kingdom. Before they can be married, Bridgette and Felix arrive, exposing Hawkmoth and his henchmen, and they are all arrested. Bridgette tells her mother she wants to marry Felix and knows how to save the kingdom. Adrien proposes to Marinette, but she says she wants to travel. Marinette leaves, but eventually returns and accepts his proposal. The four have a double wedding. And Tikki and Plagg end up together.
Whose Who:
Annaliese - Bridgette
Erika - Marinette
Julian - Felix
Dominick - Adrien
Preminger - Hawkmoth
Serafina - Tikki
Wolfie - Plagg
Queen Genevieve - Sabine
Madame Carp - Mrs. Bourgeois/Chloe
Nick and Nack - Kim and Ivan