S3, E17: With Mary (Adelaide Kane) presumed dead, Elizabeth (Rachel Skarsten) enlists Lola's (Anna Popplewell) help in taking the Scottish crown for herself, while Mary's half-brother James (guest star Dan Jeannotte) must defend her throne from John Knox (guest star Jonathan Goad). Meanwhile, Mary comes face to face with Francis's killer when she and Bash (Torrance Coombs) find themselves in the hands of a fearsome clan leader named Munro (guest star John Barrowman). Megan Follows, Ben Geurens, Craig Parker, Celina Sinden, Charlie Carrick, Rose Williams and Jonathan Keltz also star.