Set in London just prior to World War II, the film is about a middle-aged, straitlaced vicar's daughter and governess Guinevere Pettigrew (Frances McDormand), who has been fired from her fourth job. When employment agency head Miss Holt insists that she will not help her, the destitute Miss Pettigrew leaves the office with an assignment intended for a colleague, unaware that flamboyant American singer-actress Delysia Lafosse (Amy Adams) wants a social secretary rather than a nanny.