After spending a childhood safely hidden away in a monastery, a teenage Mary Stuart arrives in France where she has been sent to secure Scotland's strategic alliance by formalizing her arranged engagement to the French King's dashing son, Prince Francis. Further complicating things is Bash, Francis' handsome, roguish half-brother and Francis' mother, Queen Catherine. When the strong-willed Queen learns of a prophecy that marriage to Mary will cost Francis his life, she is determined to save her son, no matter how many others have to pay with their lives.

When Simon, an English envoy, tells Mary that the English are aware of her fragile engagement to Francis, Mary and Francis put on a show to protect their alliance. Meanwhile, when Queen Catherine learns that someone who knows about her plot to destroy Mary is still alive, she stops at nothing to make sure they are silenced for good.

When England's armies threaten Scotland's borders, Mary asks King Henry for help, but he refuses. Tomas, the son of the King of Portugal, proposes marriage to Mary, promising her aid against England if she'll abandon Francis and turn to Tomas instead. Francis puts Bash in jeopardy when he lets his feelings for Mary cloud his judgment.

Mary has to decide if she is willing to lie and sentence a man to passing in order to have King Henry let her out of her engagement to Prince Francis. Meanwhile, Francis and Bash are suspicious of Tomas' true intentions which will ultimately lead to a confrontation with disastrous results.

When Olivia, who is an ex-lover of Francis', arrives at the castle, she brings the dangers of the woods with her. Mary seeks comfort in Bash. Bash is threatened by heretics for interfering with a sacred blood rite. Meanwhile, Aylee is forced to spy on Mary when Queen Catherine blackmails her.

An attempt to scare Mary causes Queen Catherine to take drastic measures to make sure the guilty party is caught. Francis, aware of Bash and Mary's growing attraction, turns to Olivia. Bash ventures into the woods to pay his debt - the human sacrifice the pagans demand - and returns with blood on his hands. Meanwhile, Kenna comes clean with the girls about her affair with the King, to a mixed response.

Mary and Francis are forced to rely on one another when the castle is taken hostage, and Catherine shocks everyone when she makes a surprising proposal to try to save their lives. Meanwhile, Bash's mother Diane tells Bash of her plan to have him legitimized.

Nostradamus tells Mary of his prophecy that one among them will die soon, which causes Mary to make a decision that will forever change her relationship with Francis. Clarissa becomes bolder with her endeavors, while Kenna informs Catherine of Diane's plan for Bash, which ends up backfiring.

When Mary and Bash are captured and forced to return to the castle, they discover Catherine waiting and even more determined to keep Mary and Francis apart. Francis learns of the prophecy, but his determination to wed Mary changes everything: in love in politics, tearing the bond of brothers apart, and hardening Catherine's resolve to destroy Mary at any cost.

When a plot tohug Bash goes wrong, Queen Catherine is suspected of orchestrating it. Mary offers to help free a wrongly imprisoned pregnant peasant named Isobel who has a mysterious tie to Bash. Meanwhile, Lola blackmails Queen Catherine to keep her from trying to ruin Mary and Bash, whose bond continues to grow.

When King Henry accuses Queen Catherine of treason and adultery, she sets out to save her life by exposing Bash's dark past. Mary and Bash go on a quest to expose an even more deadly secret from Catherine's past. Meanwhile, Nostradamus reveals the truth about the castle ghost, Clarissa, which shocks everyone.

When Clarissa kidnaps the younger children of King Henry and Queen Catherine, Mary and Bash work with the Queen to find them, with tragic results. Meanwhile, when Lola attempts to help her brother with a debt he owes, Francis rescues her, causing the two of them to grow closer.

With a forced marriage looming, Mary must consider both her heart and her nation when deciding whom she will wed - Francis or Bash - when Francis returns to court with Lola at his side. Further complicating matters is Mary's mother, Marie de Guise, who visits the castle with her own agenda for Mary. Marie's presence worries King Henry and Queen Catherine, who have their own plan for the future of France, regardless of who gets hurt in the process.

Mary returns from her honeymoon and, suspicious of Lola's strange behavior, uncovers a deception that changes everything. Bash encounters a confused and terrified Olivia, an escaped victim of the terrors of the woods, which causes him to enlist Nostradamus for help. Meanwhile, when King Henry's odd behavior causes misfortune, he is forced to ask for Queen Catherine's aid.

The castle is abuzz with First Light, where the women of the castle mingle with potential suitors. Much to Mary's dismay, Lola is reluctant to participate in the tradition. After another unhappy incident with the increasingly erratic King Henry, Kenna fears for her safety and confides in Queen Catherine, while Bash experiences the terrors of the woods and vows to uncover the truth behind the Darkness.

When Francis reluctantly agrees to help Bash uncover the threat in the woods, he ends in grave danger, with only Bash to save him. Meanwhile, the King's madness causes chaos when a servant wins "Queen for the Day", and the King becomes obsessed with her. The King also forces a surprising, and unbreakable, union with a new couple at Court. Meanwhile, Greer gets caught kissing kitchen servant Leith, which threatens to ruin her.

When Mary learns of a secret clause in her marriage contract that her mother, Marie de Guise and Queen Catherine orchestrated, Mary and Francis embark on a dangerous plan to turn Scotland against her mother - and Mary gets her first taste of power as the Queen of Scots.

When Mary's brother James arrives in France and convinces Mary to return to Scotland, Francis is suspicious and uncovers a plot that would destroy Mary, which causes a rift between them. King Henry's downward spiral continues, leaving Penelope in charge, causing Catherine and Kenna to take drastic measures. Meanwhile, Lola becomes wary of Lord Julien's motives behind his marriage proposal.

When Mary's uncle, the Duke of Guise, arrives in France with devastating news about her mother, Mary and Francis realize they are torn between putting their own countries first or saving their marriage. With the English throne in jeopardy, King Henry hatches an elaborate plan that will end in disaster. Meanwhile, Bash and Kenna solidify their marriage and begin to trust one another.

Mary enlists a mercenary to help her, which forces her to realize there are sacrifices and lives she is willing to risk to save her country. Francis embraces his role as Dauphin to lead France in a brutal battle against England, and finds a new ally in Leith. Meanwhile, as Lola grows closer to Lord Julien, she gets increasingly suspicious that he is going to betray her.

Mary and Catherine form an unlikely alliance when deciding how to deal with the increasingly manic King Henry, which puts Francis in jeopardy. Bash finds a boy who lived to tell about his encounter with the Darkness, which makes Bash determined to end it for good at any cost. Lord Julien reveals the truth about his motives, and Lola, blinded by love, finds herself in a dire situation after she attempts to protect him.

When the King's madness and cruelty reaches a fevered pitch, Mary and Francis take action. Their choices could change the course of history, but an unforeseen terror brewing in the woods could cost them, and their friends, everything. Mary makes a drastic decision when she learns Lola is going through a life-threatening labor at a location outside of the castle.