Sois Belle et Tais Toi is more popularly known by its American-release title Be Beautiful but Shut Up. Mylene Demongeot plays a birdbrained young lady who gets mixed up with a gang of juvenile-delinquent smugglers. The crooks use the heroine as their go-between, intending to leave her holding the bag if and when the cops show up. Fortunately, a handsome police inspector (Henri Vidal) catches on to their scheme. One of the screenwriters for Sois Belle et Tais Toi was no less Roger Vadim. When the film was first released, its direction was often erroniously credited to Marc Allegret.