Louis welcomes Leopold, the Emperor vanquished of the Holy Empire, to Versailles. Philip, victorious in the war, was given the task of selecting prisoners to deport them to the colonies. But the presence of a mysterious prisoner with a masked face awakens his suspicions.

Louis and Leopold compete for control of Spain, and Maria Theresa plays a dangerous game by supporting her lover rather than her husband. Philippe continues his investigation on the man with the iron mask. In the salon, the position of Maintenon, the king's pious favorite, is threatened. In Paris, the people refuse to pay taxes.

In Paris, Fabien finds it difficult to maintain order. At court, Louis rejects Maintenon when his troubled past is exposed to the light. Philippe is attacked after spotting the man with the iron mask. At the Vatican, Cardinal Leto wishes to hand over the King of France in his place.

Louis has Marie-Therese confined to the castle, suspecting her of conspiring against him with Leopold. Louis raises indignation by imprisoning a prominent Protestant philosopher. In Paris, Fabien is released in exchange for prisoners, but Louis asserts his authority by having one of them executed as an example.

Maintenon returns to the palace and encourages Louis to put his plans into action. Louis wants to discredit Leopold, and makes a secret pact with Barek, the Ottoman emissary. Philippe understands that the Church is at the origin of the conspiracy of the man in the iron mask, and suspects Louis to take part. Marie-Thérèse falls seriously ill.

Louis changes tactics to counter Leopold, but he discovers a new opponent with Cardinal Leto, attending the funeral of the Queen. Meanwhile, Philippe discovers the unthinkable on the man with the iron mask.

The burning question remains: who is the man with the iron mask? Leto decides to bring the man with the iron mask to Versailles, but Bontemps feels the danger. With the help of Fabien, he removes the prisoner and brings him to Louis and Philippe. The truth is finally revealed.

While Philippe wants to send the man with the iron mask to the colonies, Louis knows that it must be eliminated. Meanwhile, the revolt rages in the streets of Paris, and the loyalty of Fabien is put to the test in the face of the violence of the King. Leto takes advantage of Louis' weakness and the threat of excommunication.

Fabien knows Louis has killed the prisoner and deduces the truth about the Man in the Iron Mask. Philippe decides to leave the court. Leto convinces Maintenon to support the marriage of Louis and the Infanta Isabella. But against all odds, Louis marries Maintenon and proclaims himself head of the Church of France. Louis accelerates his campaign of expansion in Europe and persecutes the Protestants.