"Reign", the period drama set in 15th century England, is not just about sibling rivalry and the quest for power, it explores the broader theme of women in politics, love and religion at a time of uncertainty in England. Amidst all of this is the troubled relationship between Mary Queen of Scotts and Queen Elizabeth I. This will be the crux of the plot in season 3 episode 9 titled "Wedlock."

In the latest episode, Mary (Adelaide Kane) is forced to see a future with the Prince of Spain, Don Carlos. The weak prince, who appears handicapped, does not have a place in Mary's heart and what's more, she wonders if Don Carlos is indeed as sick as he portrays himself to be.

In season 3 episode 9, Mary and Gideon (Ben Guerens) will carry out an investigation into the Prince's health. However, before any of this could happen, the Queen of Scotland is told that Elizabeth is going to marry Don Carlos (Mark Ghanimé). In the promo, a shocked Mary simply says, "Unbelievable."

Furthermore, the upcoming episode will also reveal Elizabeth's intention to kill Mary. She sends an assassin to end Mary's life, but we predict that Elizabeth's plan will not materialise. In the promo, Mary exposes her sibling's plan at the altar and points to the man who is sent to kill her.

The synopsis for season 3 episode 9 reads:

"Claude is forced to marry someone selected by Narcisse. Meanwhile, a surprising discovery is made by Elizabeth, and it could alter her reign; and Mary asks Gideon to help her confirm her suspicions about Prince Don Carlos."

"Reign" season 3 episode 9 titled "Wedlock" airs on Friday, 15 January at 8pm on The CW. You can live stream the episode here

Watch the promo below: