The owner of a suburban boarding school is found murdered. The culprit will be unmasked thanks to the ingenuity and courage of the good Janine and a student, named Nadine.
| Actor | Role |
|---|---|
 Dora DollJeanine - la servante | Jeanine - la servante |
 Françoise VatelNadine | Nadine |
| GGuy JacquetGérard Lambert | Gérard Lambert |
 Joël SériaOlivier Berton | Olivier Berton |
 Michel DumurLouis dit P'tit Lou | Louis dit P'tit Lou |
 Louis SeignerMonsieur Maréchal - le directeur de l'institution | Monsieur Maréchal - le directeur de l'institution |
 Georges ChamaratMonsieur Pommelle | Monsieur Pommelle |
 Marguerite PierryMademoiselle Guérande | Mademoiselle Guérande |
 Charles BayardNot listed | Not listed |
 Richard BohringerNot listed | Not listed |
 Pierre ClémentiNot listed | Not listed |
| JJacques DegorNot listed | Not listed |
 Mag-AvrilUn professeur | Un professeur |
 Maryse MartinLa directrice | La directrice |
| CClaude MercutioNot listed | Not listed |
 Marcel PérèsUn inspecteur | Un inspecteur |
| JJean RoucherNot listed | Not listed |
 André ValardyNot listed | Not listed |
| LLucien Barjon(uncredited) | (uncredited) |
| JJean-Claude Forestier(uncredited) | (uncredited) |