The Ambassador's Daughter (1956)

SYNOPSIS

De Havilland is Joan Fisk, bored daughter of the American ambassador to France. Tired of entertaining the V.I.P. wives, she comes up with an experiment. She proposes to her father and his friends that not all soldiers are crude and untrainable in social graces, and, to prove it, accepts a date with an American G.I. (Forsythe). But as the night progresses and romance begins to blossom, she realizes that she has gotten herself into a sticky situation. Although nearing forty, de Havilland gives an inspired, believable performance as the young ingenue.

(Source: available at Amazon AMC Classic Movie Companion).