To punish three troublemakers, Albert Castraing, their French teacher, gives them an essay to do, in which they must imagine what their lives would be if they were suddenly transformed into adults. The next morning, the three twelve-year-old boys realise to their amazement that...they HAVE BEEN transformed into adults! As for they parents they have become...KIDS! It is the beginning of a series of mishaps for Joseph, a Jew, Igor, a catholic and Nourdine, an Arab...