How do you french kiss?

French Kiss tells the story of Kate (Meg Ryan), a fastidious young lady who knows exactly what her future will be: she will marry a Toronto doctor named Charlie (Timothy Hutton) and live happily ever after as soon as he comes back from a business trip to Paris. Not part of her plans was her man running off with a beautiful French seductress. Determined to get him back, Kate overcomes her fear of flying and boards a flight for Paris where she is seated next to Frenchman Luc Teyssier (Kevin Kline), a crude petty thief whom she is forced to tolerate for the next few hours of the flight. Luc hides a stolen vine and necklace in her purse to get it past customs, and then accompanies her across France in order to get the necklace back, under the pretence of helping her win back Charlie.