Charles Van Horn, son of rich and powerful Théo Van Horn, calls upon his former teacher Paul Régis to help him solve the mystery of his recurring bouts of amnesia.

Jean, nicknamed Brasse-Bouillon, and his brother Ferdinand live with their paternal grandmother, who is responsible for their upbringing. But when their parents returned from Japan, they settled in Belle-Angerie and resumed their role with the children, while their grandmother had to leave for cousins. The boys soon come up against the contempt of their mother, Marthe. Faced with this shrew, whom he nicknamed "Folcoche" (a contraction of "madwoman" and "pig"), Jean decided to join the resistance.