Catherine is suspicious that Mary and Condé are having an affair; Francis becomes ill; Bash's life is in peril; Leith is forced to guard Claude.

Francis and Mary are forced to set aside their differences and determine the extent of Condé's betrayal; Catherine teaches Narcisse a lesson; Bash brings Delphine to the castle.

Elizabeth must deal with the political backlash of harboring Catherine in England, while Catherine is imprisoned upon her return to France. Mary is forced to make some difficult decisions about securing Scotland's future and Lola is conflicted in her feelings for Narcisse.

Mary realizes she must help Catherine in her quest to become regent, even at the risk of hurting the alliance with Scotland. Claude is determined to help Leith marry while Elizabeth struggles with the prospect of losing Dudley.