Mary arrives in France to formalize her arranged marriage to Prince Francis, but complications arise when she meets his attractive half brother and skeptical mother in the series premiere of this historical drama about young monarchs.

Mary and Francis play up their romance after an English envoy expresses doubts about their union. Elsewhere, Catherine seeks to eliminate an individual who's aware of her scheme to destroy Mary.

Nostradamus shares with Mary his prophecy about a death, which leads Mary to make a big decision concerning Francis. Meanwhile, Clarissa gets brazen as she pursues her goals; and Kenna tells Catherine about Diane's intentions regarding Bash.

Mary must decide whether to marry Bash or Francis, who returns accompanied by Lola. Meanwhile, Mary's mother visits and pushes her own agenda, and her mere presence in the castle troubles both Henry and Catherine.

Mary and Francis take drastic action in response to Henry's madness. Meanwhile, a terror in the woods puts everyone in peril; and Mary makes a bold choice when she discovers Lola is in the midst of a life-threatening labor.

Francis and Mary's new rule is threatened when a plague ravages the land. Kenna's life is at risk. Greer discovers something shocking about Leith.

A powerful and dominating Lord learns Mary was responsible for his son's death, he demands retribution. Francis and Lola return to the castle with their new son.

Shadowy riders have attacked a shepherd, Lord Conde and Bash investigate. Mary reconsiders her relationship with Lola. Leith returns to court.

Bash and Francis come up with a daring plan whilst Mary has a surprising proposal for Claude.

As Mary and Francis investigate who was behind the poisoning of King Henry (Alan Van Sprang), they unearth secrets of the past which force Mary to confront her feelings for Conde as she attempts to move forward. Catherine finds herself in the middle of a romantic triangle when the Duke of Guise (guest star Gil Darnell) returns, which forces Narcisse (Craig Parker) to commit a hideous act out of desperation. Meanwhile, Greer (Celina Sinden) finds herself in a situation she never fathomed in order to survive.

Mary's mother (guest star Amy Brenneman) returns to advise Mary that her throne is in jeopardy. Mary makes a shocking proposition to Conde, along with a bold move to reclaim her throne. Francis moves closer to Lola after a setback with Mary, while King Antoine (guest star Ben Aldridge) makes Kenna an interesting offer. Megan Follows, Craig Parker, Rose Williams, Celina Sinden, Torrance Coombs and Jonathan Keltz also star.

As Francis thinks Mary is turning against France, she risks everything to take Condé down; Catherine meets with Queen Elizabeth; Kenna's secret will seal the fate of her relationship with Bash.

Queen Mary struggles to hold on to her power in Scotland amidst Queen Elizabeth's campaign to sabotage her with the help of a new ally in Queen Catherine. Meanwhile, with Francis' fate at odds and Elizabeth distracted by temptation in her first love, Robert Dudley, both queens struggle to rule.

Mary makes a bold move to defend her reign in Scotland, which results in a battle royale with her cousin, Elizabeth. Lola is accused of a heinous crime and suffers the drastic consequences. Meanwhile, back in France, Catherine finds that Charles has returned a changed man after paying a price for his mother's relentless quest for power.

Gideon shows Mary what life could be like if she chose love over country. Catherine fights to cover King Charles' increasingly erratic behavior, while Claude finds an enemy in her sister Leeza.

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.

In the series finale, Mary changes the course of history with a decision she makes, and her perilous move for survival causes her to have a stunning realization. Meanwhile, Elizabeth steadies herself for war and becomes the instigator in Mary's demise.