The book centers around a young Australian woman named Cassandra (along with her grandmother, Nell O’Connor) whose life turned upside down when she learns that she was adopted. She learns that her grandmother Nell was found alone on a wharf holding a suitcase and a book of fairytales. These are her only clues to her real identity. Cassandra learns that Nell had a secret house on England, and her curiosity urges her to relocate to find more about Nell.
When Cassandra arrives there, she learns that Nell was desperate to find her true family, who she believed lived in England. Cassandra later discovers that Nell’s real name was in fact Ivory Walker. Cassandra also works on renovating the run down house. As she is cleaning, she discovers a secret garden that leads to Blackhurst Estate.
Cassandra discovers that Blackhurst Estate belongs to Georgiana Montrachet and her brother Linus. The locals inform Cassandra that Georgiana ran away with a common soldier, thereby tarnishing her family’s reputation. The only person she kept n contact with was her bother Linus. She now has two children, Eliza and Sammy, and is living in destitute in London. However, Sammy dies and Eliza is brought back to Brackhurst House by her uncle Linus.
Eliza and Linus’ daughter Rose become best friends, but Linus’ wife, Adeline detests Eliza. Rose is then separated from Eliza and relocated to New York, where she gets married to Nathaniel Walker. However, as she is barren, she urges Eliza and Nathan to have sex in order for Eliza to carry her baby. The baby is names Ivory Walker/Nell. However, Nathan and Rose die tragically and Eliza is left with Ivory.
Eliza decides to move to Australia with Ivory. However, she goes back to her old house to retrieve her mother’s brooch and leaves Ivory on the ship. However, Adeline is worried that people will find out that Eliza is the true mother of Ivory and not Rose, so she has her kidnapped. When Eliza wakes up from her unconsciousness, she realizes that Ivory was still on the ship and has travelled alone to Australia. She then kills herself.
Cassandra learns that the secret garden is where Adeline buried Eliza, under the tree that Eliza and Rose planted.