Hepburn and Grant met for the first time in a Paris restaurant just before filming began on Charade, introduced by their mutual friend and director Stanley Donen. Audrey, admitting she was terribly nervous, knocked over a bottle of red wine, staining Grant's cream suit. Donen wrote the funny incident into the film, when Hepburn as Reggie accidentally tosses a scoop of ice cream onto Grant's jacket. Like all Hepburn's leading men, with the possible exception of Bogart, Grant was instantly charmed by her, telling a reporter after filming All I want for Christmas is another movie with Audrey Hepburn.

As evidenced in Grant's playful letter, the co-stars remained affectionate friends. Years after Grant's death in 1986, Hepburn reminisced Cary - such a lovely souvenir in my life... He had me down flat the minute he met me. I think he understood me better than I did myself.