In a quaint French village celebrating World Laughter Day, Emilie, a 10-year-old prankster, investigates why everyone bursts into laughter around Mr. Dupont, the baker. She discovers he added a herb to his croissant dough, causing uncontrollable laughter. With her pet goose, she concocts biscuits to balance the herb's effects, restoring peace and fostering community through shared laughter.