Le règlement intérieur

One day in December 1979 in Hersange an imaginary town in the East of France an entire class is missing and returns the next day as if nothing had happened Was it a concerted action or a coincidence A tormented principal a policeman with a head for maths and an unabashed teacher investigate in a creeping equivocal atmosphere littered with false clues How can an apparently minor event become a real enigma