In the 1939-set romantic tale, Miss Guinevere Pettigrew (Frances McDormand), a middle-aged London governess, finds herself unfairly dismissed from her job. An attempt to gain new employment catapults her into the glamorous world and dizzying social whirl of an American actress and singer, Delysia Lafosse (Amy Adams). Within minutes, Miss Pettigrew finds herself swept into a heady high-society milieu - and, by the end of the day, discovers her own romantic destiny.