Catherine and Mary flee Don Carlos' chambers following their incident as Reign Season 3 Episode 8 begins. As they walk through the tunnels, Catherine begins concocting a story to cover their connection to his accident. Expecting she may be investigated, Catherine tries to get rid of her poisons telling Mary she's suspected in Francis' death when Narcisse knocks on the door.
Narcisse uses the rat in Lola's bath as proof that Catherine could have murdered Francis and Mary watches as the lovers quarrel. Mary sees the glint of lying in Narcisse's eyes and knows that Catherine is teling the truth. Mary's conscience becomes conflicted when she learns that Catherine and Narcisse have been sleeping together again.
Lola refuses to accept the fact that Narcisse could be behind the rat in her bath and the note in its mouth. She can't believe that her husband would do something which would make a mockery of their marriage.
Mary receives information from her new counsel from Scotland, Lord Cunningham. There are border skirmishes happening in Scotland over barley crops and hostages have been taken. Cunningham urges Mary to continue pursuing Don Carlos and she tells him that an alliance with Spain is off.
One of Don Carlos' advisors suspects that someone within French court has corrupted Don Carlos. He wants Greer brought to him believing her ladies to be the sources of corruption. From Greer, Mary learns that one of the servants overheard two women with Don Carlos shortly before his accident, but their identities have not yet been determined.
Catherine visits Claude to say goodnight and learns that Claude has been summoned to the inquest about Francis' poisoning. Claude promises not to tell the inquest about being poisoned by her mother if Catherine will convince Charles to let her choose her own husband.
From the Duke of Alba, Mary learns that Don Carlos' advisors have all known of the prince's proclivities for quite some time and have been traveling along behind him to keep rumors under wraps and away from the king. He and Mary agree never to speak the truth of Don Carlos' death to King Phillip so that Mary can stay removed from the scandal.
Bash catches Catherine trying to leave the castle and stops her, revealing that he has been sent by Mary to help her. Catherine and Mary learn that Don Carlos will survive his injuries and fear he will wake up and tell a different story. Catherine wants to kill the prince, but Mary wants to tell him the truth.
Lola testifies in front of the inquest and after sharing her story about the rat, Cardinal Morel commends her. Then she tells Narcisse that Mary told her it was he who put the rat in the tub in order to force her to marry him. Lola gets a letter from her mother telling her that her father and brothers have been taken hostage by the English and Narcisse promises to return her family safely.
Don Carlos wakes up with Mary and Catherine at his side. He remembers Mary and calls her pretty and it's clear he has no memory of the previous night, nor can he remember anything else.
Mary and Narcisse speak with Elizabeth's Ambassador and find that Elizabeth will release the prisoners if Lola visits her at court. They reject the offer. After the Ambassador leaves, Mary and Narcisse argue over how to respond. Narcisse wants to send in a military unit but Mary wants to explore diplomatic options.
Claude is summoned to testify before the inquest once more. One of her ladies handed over her diary to Narcisse where she had written about Catherine's poisonous soup. Narcisse commands her to face the Parlement de Paris to be tried for Francis' murder.
Mary disguises Catherine as young boy and takes her out of the castle so she can avoid the trial until Mary can clear her name. Catherine suggests Mary consider marrying Don Carlos, even in his condition, to save Scotland because Narcisse does not honor the alliance between their countries.
While having a scribe dictate a letter to her mother, Lola questions him about his calligraphy and whether he might have written the note. He denies it but tells her they are all trained in the same penmanship.
Bash meets Catherine on the road where she learns that Francis' embalming was done hastily. They believe Francis' liver might still be inside his body, thereby proving Catherine was framed.
Narcisse kills the scribe who can tie him to the rat and note hoping it will be the last crime necessary to cover his tracks. Instead, it ends up being the thing which drives Lola away from him completely.
Scottish Lords arrive in French court and beg Mary to return to the throne in Scotland. They bring with them children starving from the crop blight in hopes that it will jar her into coming home.
Catherine returns to court with Bash at her side, bringing with them Francis' body to prove that his liver is still intact. Narcisse promises to reverse the decision of the inquest and the Cardinal apologizes on behalf of the Vatican.
After speaking with Lola about her decision to go to England to save her family, Mary agrees to marry Don Carlos and King Phillip accepts their engagement.