The Horse in the Gray Flannel Suit (1968) on Netflix

Plot summary

Fred Bolton is an advertising executive in Lakeville, Connecticut, a widower living beyond his means. His boss gives him twenty-four hours to devise an original campaign for Aspercel, an over-the-counter indigestion medicine sold for the client Allied Drug and Food. Tom Dugan, the chairman of the client, wants a campaign with class and dignity for sour stomachs. Fred's daughter Helen, a teenager, loves horses, takes riding lessons and has competed, but the family cannot afford a horse of its own, and Fred is allergic to them. Fred's plan joins both aims: buy a good horse, give it the medicine's name, and let Helen ride it, since the horse needs prize ribbons before its name reaches the newspapers. Helen's riding instructor Suzie helps, along with Ronny Gardner, a teenager smitten with Helen.