Kathleen 'Kick' Kennedy, a recent arrival to England from Massachusetts, is already a huge hit in 1930s London society. Her status as the daughter of an ambassador puts her at the centre of the most elite social circles but being an American and a Catholic sets her apart, something she only comes to realise when she falls for Billy Cavendish, the future Duke of Devonshire. Their families will never approve the match - if her parents find out about their romantic attachment, she risks being sent back to America. Lady Brigid Guinness has no interest in love, marriage or society connections. Her brother-in-law Chips Channon, always seeking to increase his political capital, is keen for her to befriend Kick but Brigid has no interest in showing a brash American around town. When Chips invites both Brigid and Kick to his country estate in Essex however, neither of them is given a choice in the matter.