Lucien Delaubert, exploring the attic of his ancestral manor, discover an ancient journal revealing the existence of a map leading to a lost Renaissance treasure. With his friend Eloise, they begin a quest through their city, solving puzzles and deciphering clues hidden in historical places. Their adventure leads them to meet an enigmatic librarian, Mr. Lefèvre, and to experience a nocturnal infiltration into a museum, full of comic adventures.

 

Eventually, the treasure turns out to be local historical artifacts, symbolizing the cultural richness of their city. Lucien and Eloise organize a exposure to share their discovery, where a humorous incident with a historic cake collapsing brings laughter and lightness to the event. The exhibition is a success, strengthening their friendship and their love of history and adventure.

 

The discovery of an old key marked “Your Heritage” in an unopened box reignites their curiosity. This new find leads them on a new quest within the manor, promising new adventures and discoveries about the history of the Delaubert family.