The King goes to war as an unlikely intruder locks down the castle. Mary and Francis realise they must overcome their argument and work together to save everyone at court.
Henry plots to kill Francis, and begins his efforts to woo and marry Mary. Leith returns to win Greer back. Lola goes into labour. Francis, Catherine and Mary plan a coup. The Darkness returns for Pascal.
While Francis and Bash are out trying to find Montgomery the Protestants are becoming more and more restless. Mary is alone at the castle and Protestant men storm it, leaving Mary in distress. Castleroy doesn't realise what he has been funding while he thought it was schools.
As Francis thinks Mary is turning against France, she risks everything in order to take Conde down; Catherine meets with Queen Elizabeth and has a proposition for her; Kenna's secret will seal the fate of her relationship with Bash.
Charles escapes the Red Knights, at the cost of an old friend. Mary returns home, but not everyone is happy. Narcisse's attempt to rescue Lola takes a twist when she chooses to carry out a risky mission.
As the king Francis returns to life, Nostradamus is back with a new prophecy about his death. Meanwhile the English ambassador is offering Mary a chance at peace by signing away her claim to the English throne.
Lola tells Mary she may have a chance to get to Scotland. A murder takes place and Catherine is framed for it. Mary must decide if she should help Catherine or leave for Scotland. If Mary helps Catherine it could eliminate the possibility of safe passage to Scotland.
When Mary and Bash are captured they are forced to return to the castle, tearing the bond of brothers apart and hardening Catherine's resolve to destroy Mary and Francis' love at any cost. Francis learns of the prophecy,