Stéphane, a struggling actor, arrives at the renowned Avignon Theatre Festival with his troupe to perform a boulevard comedy titled Ma sœur s’incruste. Amidst the festival's bustling atmosphere, he encounters Fanny, a rising star performing in a classic play. Captivated by her, Stéphane inadvertently lets her believe he's portraying Rodrigue in the prestigious Le Cid by Corneille. To win her affection, he perpetuates this fabrication, leading him into a web of lies that quickly spiral out of control.