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'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.
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.