Queen Mary, unsure who to trust, tests her brother James to ensure his loyalty after hearing of his meeting with John Knox. Queen Elizabeth agrees to help Lord Darnley, in an attempt to sabotage the powerful suitor's relationship with Mary.
Mary discovers there is a leak within her inner circle and sets out to uncover the traitor. Queen Catherine goes to extremes to regain some of her lost power, while Queen Elizabeth attempts to use Narcisse to further her quest for supremacy.
Mary must choose between love and country, while Gideon attempts to show her why she should choose love. French court is in chaos as Catherine's daughter Leeza returns home, directing her animosity towards her sister Claude. Catherine struggles to cover for Charles as his behavior becomes increasingly erratic.
When Lord Darnley surprises Mary with a visit in Scotland, Mary sees a glimmer of a union that could be more than just political. Elizabeth fights to gain allies in her favor and Catherine must work to get Claude back on track by finding her a new husband.
In order to get Mary (Adelaide Kane) to agree to a marriage, Lord Darnley (Will Kemp) must demonstrate his loyalty when she voices her concerns about his true intentions. Catherine (Megan Follows) and Narcisse (Craig Parker) work to repair King Charles' (Spencer MacPherson) reputation after rumors spread about his strange behavior and threaten the throne.
Mary (Adelaide Kane) must deal with the political repercussions of a potential marriage to Lord Darnley (Will Kemp) and King Charles (Spencer MacPherson) disappears, leaving Catherine (Megan Follows) to pick up the pieces. Elizabeth (Rachel Skarsten) comes to Gideon's (Ben Geurens) aid, while Claude (Rose Williams) receives an interesting proposition. Craig Parker, Dan Jeannotte, Jonathan Goad and Celina Sinden star.
When Darnley (Will Kemp) gets a surprise visitor, his marriage to Mary (Adelaide Kane) hangs in the balance. Elizabeth (Rachel Skarsten) learns her attempt to stop Mary backfired. Meanwhile, Catherine (Megan Follows) and Narcisse (Craig Parker) find King Charles (Spencer MacPherson) and must convince him to return to the castle.
As Mary's upcoming wedding looms, a terrible tragedy pushes Mary and Darnley apart, forcing Mary to enlist in Catherine's help. Elizabeth encounters a traitor to Spain, who petitions her to support an expedition to the New World.
Mary and Darnley wed in a lavish affair, which proves to be a successful decision in regards to her political standing. James makes an interesting discovery about Greer, while Elizabeth frantically tries to salvage England's power.
As Mary strategizes ways to take over the English throne, Elizabeth struggles to find an appropriate suitor to marry. Meanwhile, James gets caught up in a scheme orchestrated by John Knox and has to deal with the tragic aftermath.
Mary and Darnley are at odds as they put their plan to seize England into action. Elizabeth is conflicted about her feelings for Gideon as she attempts to find a Catholic to marry. Catherine's son Henri (guest star Nick Slater) attempts to claim the throne from Charles with the support of Spain and Narcisse.
After a tragic earthquake hits Scotland, Mary must face John Knox (Jonathan Goad) amidst claims that she isn't coming to the aid of her people. Elizabeth takes drastic measures after she is discovered with Gideon, while Charles makes a decision that backfires.
Darnley teams up with John Knox to strip Mary of her throne, which will leave a close friend of Mary's dead. Elizabeth must banish Gideon from court at the request of her future husband, while Charles takes a bold stance against his brother Henri (guest star Nick Slater).
Mary makes a decision that will change the course of history, forever shaping the fate of her nation, her crown, and her newborn son. Mary's perilous move for her survival causes the stunning realization that perhaps she is not the only one who may not survive. Meanwhile, Elizabeth steadies herself for war and will become the instigator in Mary's demise while later realizing she and Mary might be more similar than either thought.