Queen Mary discovers there is a leak amongst her advisors and sets out to uncover the traitor. Queen Elizabeth enlists in Narcisse to further her quest for supremacy. Meanwhile, Catherine takes desperate measures to regain some of the power she has lost.

When Lord Darnley surprises Mary with a visit in Scotland, Mary sees a glimmer of a union that could be more than just political. Elizabeth fights to gain allies in her favor and Catherine must work to get Claude back on track by finding her a new husband.