Martenot is a father fiercely hostile to cars, to the great shame of his brother-in-law Bastien, garage owner. Appointed deputy bank manager in Paris, Martenot goes to the obvious: the excessive fatigue caused by the train and the bicycle are detrimental to his career. He then moved to Paris to take driving lessons during the week, but dared not admit to his family that he failed the test. A recent conquest in Paris gives him a false driving license, but this precaution does not increase his dexterity - In addition, unforeseen events complicate his life; forced to urgently drive a pregnant woman to the clinic, he is observed by his brother-in-law. He shares his doubts about Martenot's loyalty to his sister. She immediately sends a telegram to her husband to inform him that she is asking for a divorce. But Martenot, who became, through the local press, by virtue of his devotion, the hero of the day, will see his star shine in the firmament of the bank. Finally, he will pass the permit and everything will be back to normal.