Henry returns from Rome unsuccessful, and accuses Catherine of adultery with Nostradamus with the goal of executing her. Catherine learns about Isobel's baby but the pagan mark on her foot is gone, making her useless as evidence against Bash. Mary and Bash learn that years ago Catherine had an affair and gave birth to a child before Francis was born. They inform Henry, who realizes that the father is his friend, Richard Delacroix, and has him imprisoned. Henry also rejects Catherine's attempts to out Bash and Diane as pagans, as he already knew about their heritage. Catherine has an encounter with Clarissa and, upon questioning Nostradamus, learns that the girl is a foundling who was disfigured by attempts Nostradamus' father made to remove a birthmark on her face; Clarissa is Catherine's daughter. Catherine attempts a murder-suicide with Mary, but Clarissa saves both of them, and Catherine is taken away to the tower to await her execution.

Mary enlists a mercenary to help her, which forces her to realize there are sacrifices and lives she is willing to risk to save her country. Francis embraces his role as Dauphin to lead France in a brutal battle against England, and finds a new ally in Leith. Meanwhile, as Lola grows closer to Lord Julien, she gets increasingly suspicious that he is going to betray her.