Penelope Benson, known as Penny, is both romantic and determined. Put in a select boarding school by her mother, she takes advantage of a trip to Paris to get away from it all and live her own life. That's how she meets Antoine du Merlet, whom she takes for a young hoodlum when in fact he's a police superintendent. She spends the night at his place, which leads to a number of setbacks for poor Antoine, who is stigmatized by the headmistress, abandoned by his mistress and has to face a strip-tease session starring the unconscious Penny... But Penny's a spicy one and Antoine's a nice guy, so... !
