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 launches a counterattack on the conspirators. Elizabeth suffers a setback that turns her world upside down.

Mary has a difficult childbirth that leaves both her and her child's life in danger. Elizabeth learns that the death of someone close to her was caused by someone in her inner circle.