A lady-in-waiting met her demise and a wedding was doomed on the midseason finale of "Reign."

In "Fated," Mary Tudor, the Queen of England, is ill, and Mary Queen of Scots (Adelaide Kane) is the next in line to the throne. King Henry (Alan Van Sprang) therefore decides that Mary and Francis (Tony Regbo) should be married, ensuring the alliance of their two countries. Mary and Francis, who had recently slept together, are very happy with the arrangement.

However, Catherine (Megan Follows) is desperate to prevent the marriage, so she gets Nostradamus (Rossif Sutherland) to tell Mary that he is having visions of Francis' death in the hopes that Mary will be too scared to enter into the marriage. So Catherine tells Mary that the marriage will inevitably lead to Francis' death.

Nostradomus confirms to Mary that Francis cannot live unless she bails out of the marriage, and that one of her ladies-in-waiting will die.

Kenna (Caitlin Stasey) then overhears the plot to have Bash (Torrance Coombs) legitimized, which would change the line of succession. Kenna gives that info to Catherine to destroy her arch rival, Diane (Anna Walton).

Catherine confronts Diane, and threatens her into leaving court forever and poisoning Kenna on her way out. The camera cuts away as the audience sees a poisoned cup of tea passed around between the ladies-in-waiting.

It's soon revealed that Aylee (Jenessa Grant) is the one who drinks the poisoned beverage. As Aylee stumbles down the hall, Clarissa (Kate Boland) walks behind her, and eventually pushes Aylee down a set of stairs to ensure her death.

Mary sees that Aylee has died, as the prophecy predicted, which leads her to believe in the veracity of the visions. It's also revealed that Diane was not the one who poisoned her.

Diane convinces Bash to flee from court until she smooths things over with Henry, and it's then clear that Clarissa did the poisoning, not Diane. Clarissa claims she killed her to save Mary because Catherine would likely have killed Mary if Francis died because of their marriage.

Mary, who is frightened by the prophecy coming true, flees from Francis, without telling him the real reason why.

Mary meets Bash in the stables, and they both realize they are running away at the same time, so they decide to run away together. Francis goes running after Mary to see her riding off alongside Bash, which makes it look like Mary left him for Bash.

When "Reign" returns on Thursday, Jan. 23, the Mary love triangle becomes more complicated, and King Henry is forced to make some bold choices for his kingdom and all of France. 

Watch the promo for "For King and Country" below, which airs Thursday, Jan. 23 at 9 p.m. on The CW.