Jean Lerat de la Grignotière is as full of himself as his name is long. Heeding (somewhat reluctantly to be true) the call of the Motherland he goes to the barracks where he is to accomplish his military duty. Posted to Corporal Bourrache's platoon he is surprised to meet there...Joseph, his own servant. Making blunder after blunder Jean gets hazed by his comrades and punished by his officers while Joseph's adaptation to military life is as smooth as can be. All this does not prevent the young snob from courting Catherine, the colonel's daughter, not very successfully at the beginning. Things start shaping better when he accepts to play a part in "Tire-au-flanc", Mouëzy-Eon's famed comedy. Interpreting the servant while Joseph plays his master, the successful beginner at long last becomes popular among the other soldiers and gets Catherine's hand as a bonus.