After a long hiatus, "Reign" will return later this month to The CW with a new threat lurking inside the French Court.

According to the synopsis for the episode, titled "Succession," Mary (Adelaide Kane) must quickly find the right suitor before the upcoming coronation of Charles (Spencer MacPherson), who will inherit the throne after Francis's (Toby Regbo) death.

But Mary's desire to have a strong alliance will not be the only issue in the upcoming episode as the identity of the person who is responsible for Elizabeth's (Rachel Skarsten) poisoning could be revealed.

The official synopsis for "Reign" episode 18 reads:

"Mary must find a powerful suitor to align herself with as Charles's impending Coronation looms. Lola (Anna Popplewell) stumbles upon the identity of Elizabeth's poisoner, while Catherine (Megan Follows) becomes a new kind of victim for the castle's serial killer."

The synopsis confirms that the French Court has been infiltrated by a mass killer. But viewers still want to know the reason why that person is murdering the people in the French palace. It would also be interesting to know if the killer is working for another person to cause alarm within the French Court.

The episode will also show that Mary is contemplating leaving France to return to Scotland. But this could be another challenge for the Queen of Scots, since her people are already fuming mad at her and burning her effigies in the streets. However, Mary seems determined to get her people back as seen in the trailer where she states that she is ready to "fight fire with fire" if she has to. Will she really leave the country of her late husband and begin to reign over her own kingdom?

"Reign" season 3 episode 11 airs on The CW on Monday, April 25.