During the Season 3 finale, the foundation of the war between Mary and Elizabeth were finally laid down.
Lola conspired with a Scottish assassin to kill Rachel Skarsten’s Elizabeth, but the attempt failed and they were captured. Elizabeth then has Lola executed by public beheading, which Narcisse witnessed.
Meanwhile, Mary consolidated her power in Scotland and successfully used the suicide of a Catholic priest as propaganda in gaining support. Gideon arrives in Scotland as part of an English delegation and he and Mary resumed their affair.
Upon learning of Lola’s execution, Mary vows to take Elizabeth’s throne and asks Gideon to help her. James figures out that John Knox was behind the order to assassinate Elizabeth, but has no evidence.
Bash leaves Mary in order to join the druids and hone his supernatural powers while Charles safely returns to the French court and ousts her mother, Megan Follows’ Catherine as regent.
Catherine retaliates by parading Henry, who is next in line to the throne. Catherine also gave her blessing to Claude and Leith to get married, but Leith is betrayed and killed by the machinations of Lewis Kirk’s Martel de Guise.
In the end, Elizabeth asks Robert to marry her but is dismayed to learn that he’s already married to Lettice Knollys.