Fracois [sic], a nuisance of a little girl, has fallen for Lupin, even going so far as to place an advance-warning message on his behalf in the newspaper. She wants Lupin to replace the real Oppenheim Rose, a ruby which her father, a jewelry appraiser, switched with a fake. But he's up against the Louvre's maximum security unit. The girl is determined to succeed somehow, but Lupin takes her to school. What will happen tomorrow?