In the kingdom of Valmont, Princess Elise Beaufort lives surrounded by strict rules, while Anastasia Clément dreams of becoming a musketeer. When their paths cross, they discover they are identical and decide to swap places for a month. For Elise, it is a chance to feel the freedom of the streets, escape court duties, and run from a mysterious shadow. For Anastasia, stepping into the princess's shoes means protecting the throne and proving she has what it takes to be a musketeer.
In the city, Elise works at a dress shop and connects with Damien, a baker who also dreams of becoming a musketeer. At the palace, Anastasia investigates the mystery while hiding her true identity from Céline, the lady-in-waiting.
Through investigations, sword fights, and unexpected romance, Elise and Anastasia begin to question who they truly are and who they want to become.