There is unrest in the upper class Marshwood house as Nigel (Edward Atterton), the Earl of Marshwood, is engaged to a film actress, Miranda Frayle. However, many disapprove because this would mean Nigel would be marrying below his class.
When Nigel brings Miranda home to the Marshwood estate to meet his family, Lady Marshwood's (Julie Andrews) maid Moxie (Sophie Thompson) reveals that Miranda is her sister; they devise a charade so that Moxie may meet her sister as an equal. However, when Miranda lies about her past (stating she's a cockney and that Moxie was a drunk and is now dead), Moxie finds it harder and harder to hide her identity. Meanwhile, Miranda's ex-boyfriend and fellow film star Don Lucas (William Baldwin) arrives, wanting Miranda back.