'Reign' season 3 episode 17 spoilers, plot news: Mary presumed dead; Elizabeth plots to take her crown with the help of Lola
Mary finally returns to Scotland in the upcoming episode of "Reign" season 3, but it will be far from the homecoming she expects.

To recap, last week's episode saw a Mary's (Adelaide Kane) ship sinking after a huge storm. Mary, Narcisse (Craig Parker) and Bash (Torrance Coombs) were washed ashore in northern Scotland. Elizabeth (Rachel Skarsten) learned of what happened to Mary and presumed she was dead, so she enlisted Lola (Anna Popplewell) to be in the English court permanently.
The show's penultimate episode airs this coming Monday, and it will feature Elizabeth taking advantage of Mary's unfortunate accident while traveling to her home in Scotland. According to the official synopsis of the upcoming episode 17 titled "Intruders," Mary is presumed dead following the huge storm that sunk her ship. Elizabeth capitalizes on the situation and asks help from Lola to take the crown as the Queen of Scots. With Mary away, her half-brother James (guest star Dan Jeannotte) must also protect her throne from being taken by John Knox (guest star Jonathan Goad). elsewhere, Mary and Bash end up being held captive by a fearsome clan leader who goes by the name of Munro (guest star John Barrowman), and she comes face to face with Francis' murderer.
Back in January, it was confirmed that "Arrow" star John Barrowman will be making a guest appearance in the show. Barrowman plays the role of Munro, the person who is responsible for killing the love of Mary's life, Francis. According to Entertainment Weekly, Munro is described as "a dangerous and charismatic Scottish clan leader who harbors a sinister grudge against the Queen of Scots."
Will Mary emerge victorious after everything she has been through? Find out in "Reign" season 3 episode 16 which airs this Monday, June 13 at 8 p.m. on The CW.