In the fourth-season opener, Mary tests her brother after he meets with John Knox, because she’s unsure about whom she can trust. Meanwhile, Elizabeth schemes to sabotage Lord Darnley’s relationship with Mary.
Season 04, Episode 02 – “A Grain of Deception”
Mary learns there’s a traitor within her inner circle of advisers, and she’s determined to unmask the guilty party. Meanwhile, Elizabeth seeks Narcisse’s help as she tries to expand her power; and Catherine is desperate to reclaim some of her lost power.
Season 04, Episode 03 – “Leaps of Faith”
Charles behaves erratically, but Catherine covers for him as best she can. Meanwhile, Gideon wants Mary to see what life could be like if she prioritizes love over country; and Claude and her sister Leeza become unexpected adversaries.
Season 04, Episode 04 – “Playing With Fire”
Lord Darnley surprises Mary with a visit to Scotland, which allows her to see more to their union than just a political bond. Meanwhile, Elizabeth attempts to acquire allies; and Catherine wants Claude to focus on securing a new husband.
Season 04, Episode 05 – “Highland Gamese”
In order to get Mary to agree to a marriage, Lord Darnley must demonstrate his loyalty when she voices her concerns about his true intentions. Catherine and Narcisse work to repair King Charles’ reputation after rumors spread about his strange behavior and threaten the throne.
Season 04, Episode 06 – “Love & Death”
Mary’s potential marriage to Lord Darnley has political consequences she must face. Meanwhile, Charles vanishes, leaving Catherine to handle things; Elizabeth helps Gideon; and an intriguing proposition is made to Claude.
Season 04, Episode 07 – “Hanging Swords”
Mary’s marriage to Darnley hangs in the balance when Darnley receives a surprise visitor. Meanwhile, Elizabeth’s plans backfire; and Catherine and Narcisse find Charles and attempt to convince him to return to the castle.
Season 04, Episode 08 – “Unchartered Waters”
A tragedy occurs, pushing Mary and Darnley apart as their wedding looms. Meanwhile, Mary is forced to enlist help from Catherine; and a traitor to Spain petitions Elizabeth to support an expedition to the New World.
Season 04, Episode 09 – “Pulling Strings”
Mary and Darnley wed in a lavish affair, which proves to be a successful decision in regard to her political standing. Meanwhile, James makes an interesting discovery about Greer; and Elizabeth frantically tries to salvage England’s power.