Lucie Audibert, a student of Art History, does research work on Watteau. She is persuaded that a hidden sense that nobody has ever deciphered can be found in a few of his paintings. The further she proceeds the more professor Jean Dussart - for unclear reasons - tries to discourage her. But Lucie is persistent, even stubborn, and, aided by Vincent, a mute street mime, she manages to attain her goal in spite of everything.