A high school in the thirties: most of the students are leaving for the Easter holidays. However, one of them,Brassier, an A -student ,stays for sentimental reasons. He is desperately in love with the principal's wife who does not want to cheat on her husband, and, above all, does not want the young man to ruin his good prospects. On a night he calls on her, a theft is committed, in the principal's office. Although completely innocent, the good lad stands accused. He's got an alibi, but it would compromise the reputation of the woman he is in love with.

Le jeune Brassier est amoureux de la femme du principal du collège et pour ne pas la compromettre, il se laisse accuser d'un vol commis par un camarade alors qu'il était en compagnie de la jeune femme. Les talents de détective du petit Navaille font découvrir le véritable coupable.