Viper in the Fist (1971)

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.

Unfortunately the movie Viper in the Fist is not yet available on HBO Max.