Delphine, a disillusioned humanities teacher, makes an agreement with her students : they leave her in peace, as they get A+ grades. But these excellent results turn into a nightmare when the class is qualified for the Latin World Championships, in Naples.

1967, Mardi Gras. Françoise is a seventeen-year-old boarder in an all-girls Catholic high school. Convinced that she has only one night left before her death, she sneaks out with her friend Delphine to attend a costume party and live the night as if it was her last.