Set in London just prior to World War II, the film follows a day in the life of Guinevere Pettigrew, a middle-aged, straitlaced vicar's daughter and governess who has just been fired from her fourth job.

Arriving at the luxurious apartment where Delysia is staying, Miss Pettigrew discovers that the younger woman is involved with three men: the devoted but penniless pianist Michael Pardue who has just been released from prison, the controlling but wealthy Nick Calderelli who owns the nightclub where she is performing, and the young theatre impresario Phil Goldman who is in a position to cast her in the lead role in a West End play.

After a series of complications, Delysia and Michael sail for New York aboard the Queen Mary, while Miss Pettigrew is found in Victoria Station by Joe who, now convinced that she is the woman for him, has been looking for her all night.

Within the next few years, the studio developed it as a musical to star Billie Burke in the title role but, just before filming was scheduled to begin, Japan bombed Pearl Harbor and the project was shelved.

He praised Amy Adams, saying the "screen magic" she displays "hasn't been this intense since the heyday of Jean Arthur", and he noted that Frances McDormand achieved her "metamorphosis from glum stoicism to demure radiance with impressive comic understatement.

"[9] Todd McCarthy of Variety said of the actors, "McDormand's performance slowly builds a solid integrity, and contrasts well with Adams' more flamboyant turn, which initially accentuates Delysia's constant role playing but eventually flowers into a gratifyingly full-fledged portrayal of a woman with a past she wishes to escape.