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.

When Darnley gets a surprise visitor, his marriage to Mary hangs in the balance. Elizabeth learns her attempt to stop Mary backfired. Meanwhile, Catherine and Narcisse find King Charles and must convince him to return to the castle.