In the year 1721, an audacious idea germinates in the mind of Philip of Orléans, regent of France… Louis XV, 11 years old, will soon become king, and, an exchange of princesses would allow to consolidate peace with Spain, after years of war, that left the kingdoms weakened. So Felipe marries his daughter, Mlle de Montpensier, 12, to the heir to the throne of Spain, and Louis XV marries the Infanta of Spain, Anna Maria Victoria, 4 years old. But the hasty entry of these young princesses into the French court, sacrificed on the altar of power games, will end their tranquility.