Martin from Marseille, Rolande Causse

Martin is distraught when his sister tells him that the father he lives with is not his biological father. With jazz in his ears, bravely and alone, Martin leaves Paris for Marseille, in search of this "extra" father. There he meets an old woman who claims to be his grandmother and soon encounters Sam. Is Sam his real father? Is Martin, then, also of Algerian and Italian descent?