On his return from a doctors' convention, Camille Prader is waiting for his bags in the airport terminal when Clémentine, his current girlfriend, surprises him by coming to meet him, looking radiant... Just as she tells him that she is giving everything up to live with him, Camille realizes that he has picked up the wrong bag: by mistake, he has taken that of a young musician, Juliette Graveur. Without hesitating, he seizes this opportunity to get rid of Clémentine and invents a love-affair. Little by little, despite himself, Camille gives Juliette more and more room in his life. He invents shared memories for them. He even goes as far as buying clothes for her. With each passing day, he makes the lie more and more present. Until he can no longer get rid of Juliette...