That Kind of Woman (1959)

In June 1944, Kay and Jane travel on an overnight train from Miami to New York, accompanied by Harry. Kay is the mistress of "The Man", a rich industrialist, whom they are to meet so that they can help entertain an important general. Red, a young paratrooper on leave, picks up Kay in the club car, while his buddy Kelly goes off with Jane. Kay assumes she will not see Red again, but Jane gives Kelly their New York address. Kay is smitten with Red as they spend the day in New York, and Red invites her to meet him on the evening train to visit his family.