Madeleine de Foix is arrested as the poisoner after trying to kill Fabien. Montespans baby suffers an illness. Louis faces criticism from Bossuet and Pascal. Sophie endures a terrifying experience when married to Cassel.

King Louis XIV's continued insomnia makes him increasingly volatile, meaning Marchal's loyalty counts for nothing. Claudine continues to investigate the mystery toxin, while Sophie seeks a solution to her situation.

A delegation arrives, but won't negotiate with the queen. Phillipe steps up to act as king while Louis is at battle. Fabien mourns Claudine and seeks to avenge her murder. The king's mistress takes her jealousy too far.

Louis meets Guillaume d'Orange in a relentless combat and returns to Versailles full of new energy. The court is in shock of two new deaths and Montespan feels herself increasingly isolated.

Louis ends his relationship with Madame De Montespan who full of humiliation turns to dark forces. Palatine is suffering of suspected poisoning and Cassel reveals Thomas' secret plans to the king.

Louis has Phillipe get close to the spy. This ignites the Chevalier's jealousy. Fabien learns what Father Etienne does with the children he rescues. Montespan is desperate to reclaim the king's love, but Louis falls for someone more pious.

The affair of the poisons continues. Could it even reach deep into Louis's own court?