Clément, a young business creator, has everything of a happy father: married to the pretty Alex, he is also the father of "Petit-Bonheur", his son. Despite his 30 years, he does not manage to live without his father, Paul, musician and widower, with whom he maintains very close ties. In addition to this exclusive report, the latter also takes care of his grandson on a regular basis. Two points which are not without provoking a certain jealousy in Alex. One day, "Petit-Bonheur", under Paul's care, fell down a staircase. At the hospital, where the child goes x-rays, Clément struggles to wait for exams and harshly reprimands his father. After this incident, the news is fortunately good: "Petit-Bonheur" is nothing serious and gladly finds his parents' arms. Clément then notices that his father has disappeared.