Jérôme and Sophie are "foreigners". They evolve in a world whose rules seem to them as many constraints and adopt unusual behaviors which can disorientate their interlocutors. They say they are brother and sister and many people prefer to believe them and be satisfied with this version for fear of supporting a situation that is too scabrous. Only Olivia accepts to assume the situation. Her taste for derision and her humor allow her to overcome the provocations of the couple and to take an ascendancy on them.