When King Henry accuses Queen Catherine of treason and adultery, she sets out to save her life by exposing Bash's dark past. Mary and Bash go on a quest to expose an even more deadly secret from Catherine's past. Meanwhile, Nostradamus reveals the truth about the castle ghost, Clarissa, which shocks everyone.

With a forced marriage looming, Mary must consider both her heart and her nation when deciding whom she will wed - Francis or Bash - when Francis returns to court with Lola at his side. Further complicating matters is Mary's mother, Marie de Guise, who visits the castle with her own agenda for Mary. Marie's presence worries King Henry and Queen Catherine, who have their own plan for the future of France, regardless of who gets hurt in the process.