Buckingham Palace, 1981. Her engagement to Prince Charles is a dream come true for Lady Diana Spencer but marrying the heir to the throne is not all that it seems. Alone and bored in the palace, she resents the stuffy courtiers who are intent on instructing her about her new role as Princess of Wales ...

But when she discovers a diary written in the 1800s by Princess Charlotte of Wales, a young woman born into a gilded cage so like herself, Diana is drawn into the story of Charlotte's reckless love affairs and fraught relationship with her father, the Prince Regent. As she reads the diary, Diana can see many parallels with her own life and future as Princess of Wales.

The story allows a behind-the-scenes glimpse of life in the palace, the tensions in Diana's relationship with the royal family during the engagement, and the wedding itself.