The brave Monsieur Breloque has a friend, Pierre Martel, a private detective. When the latter asks him to replace him for a while, Breloque, although having no competence in the matter, accepts. He anticipates adventures and misadventures but also happy surprises.

Mr. Gustave Bourdillon loves hopelessly the wife of the director of the institution where he is the only teacher. Soon a widow, the pretty wife of Mr. Calumet, agrees to marry the brave professor, but believes each onstant that her husband has returned in the form of his brave little dog Medor. After incredible situations and an immeasurable pursuit, Gustave Bourdillon and widow Émilie will live a deserved happiness.