The village of Sainte-Adèle has been struck by an outbreak of smallpox. The survival of the North lies in Cyprien's hands. Séraphin, now a deputy minister, and Donalda urgently return to Quebec.
Donalda opens a hospital at home. Séraphin sees the project as an opportunity to become the next king of the North by saving the villagers from smallpox, but the latter don't want to send patients to the hospital... Séraphin will have to resort to force to avoid an epidemic.
The vaccines brought back by Arthur are nearly all past their expiry dates. Donalda has a suggestion for Cyprien, one that could solve the problem. The epidemic hits Oscar with devastating results. And who is the thief prowling the village, attacking Lacour the shopkeeper and notary Le Potiron?
Rosa-Rose has also been a victim of the thief. Séraphin appoints Bidou as royal detective, in order to find the culprit. Father Caron profits from Délima's distress to have a regulation voted that makes alcohol illegal in Sainte-Adèle. Alexis proposes a strategy to compel the population to be vaccinated.
Bidou and Délima open their bar with the help of Rosa-Rose, Todore, Caroline and Jos. To take his revenge on Délima, Father Caron commits a totally unacceptable act. Furious, Alexis prepares his revenge.
It's time to celebrate the completion of Father Labelle's grand dream: the inauguration of the railway at the Sainte-Adèle station, in the presence of Bishop Fabre and Honoré Mercier. Caron asks Séraphin to clean up the village before their arrival, using whatever means necessary.
