Fond de l'Etang is a boarding school for troubled boys located in the French countryside. In the mid-twentieth century, it is run by the principal M. Rachin, an egotistical disciplinarian whose official unofficial mantra for the school is "action - reaction", meaning that there will be severe consequences for any boy out of line. This approach does not seem to be working as the boys as a collective are an unruly bunch. In turn, the teachers don't teach, but are always watching out for the next subversive act from the boys. January 15, 1949 marks the arrival to the school of the new supervisor, M. Clément Mathieu, a middle-aged man who is grasping at finding his place in life after a series of failed endeavors. Although he does find the boys an unruly lot, Mathieu does not believe in the "action - reaction" policy, and as such, butts heads with Rachin while secretly undermining the policy. Slowly, Mathieu's approach of trying to match the discipline to the crime does have a positive eff