Charles Bonnet (Hugh Griffith) expresses his passion for art by forging masterpieces -- and selling them at a hefty profit. The trouble starts when his reproduction of a prized sculpture winds up in a famous Paris museum. If experts determine that it is inauthentic, Bonnet's reputation will be tarnished. That's why his fetching daughter, Nicole (Audrey Hepburn), hires cat burglar Simon Dermott (Peter O'Toole) to steal the sculpture back before it's too late.