Edna May Oliver was borrowed from RKO by Paramount to portray the "nouveau riche" mother of precocious Mitzi Green. Edna's great rival is Louise Fazenda, mother of Jackie Searl. At first the ladies compete through their children by trying to promote the kids as movie stars; they then decide to team the children as a brother/sister act. While on vacation in London, Green and Searl escape from their overbearing parents and go off on a merry adventure with a pint-sized boy king. Forbidden Adventure was very liberally based on a short story by Sinclair Lewis.