As the origin of the blue blood comes to light, Élise must form an alliance between nobles and rebels to avert its spread.

Joseph and Katell fall prey to Donatien's sinister scheme. Charles orders Pérouse to track down Élise and Lariboise.

As Joseph continues his search for a cure, tensions come to a head between Charles and Donatien, and Madeleine defies Donatien's attempt to destroy her.