When fourteen-year-old Polly Milton goes to stay with her friend Fanny for the summer, she finds that the Shaw family's wealthy city life couldn't be more different from her country upbringing. With her plain clothes and more practical interests, Polly is out of place among a crowd focused on following the latest trends and presenting the right image. One of the few people who doesn't pressure her to fit in is Fanny's brother, Tom, but he's also one of the most annoying people Polly has ever met.

Over the next six years, Polly's annual visits challenge the Shaw family to question their values even as Polly feels pressured to conform to societal expectations, though she remains old-fashioned at heart. As Polly navigates the highs and lows of growing up, friendship, love, and fortune, her greatest challenge is being true to herself.