The Missing Sister is the seventh book in the Seven Sisters series inspired by the mythology surrounding the star cluster known as the Pleiades or ‘the seven sisters’. Looking at other reviews of this book, it seems that a lot of people were expecting this to be the final book in the series and were disappointed to find that it’s not; it didn’t bother me as I’d seen Lucinda Riley’s announcement on Twitter regarding an eighth book, but if you weren’t already aware, it’s probably best to know before you start that you will need to wait another year for all of the series’ mysteries to finally be resolved.

The first six Seven Sisters novels each tell the story of one of the adopted daughters of a mysterious billionaire known as Pa Salt who dies at the beginning of the series, leaving the sisters some clues to help them trace their biological parents. The girls all grew up together at Atlantis, Pa Salt’s estate by Lake Geneva in Switzerland, but they were born in different countries and come from a diverse range of cultures and backgrounds. They are each named after one of the stars in the cluster – Maia, Alycone (Ally), Asterope (Star), Celaeno (CeCe), Taygete (Tiggy) and Electra D’Aplièse. There should have been a seventh sister, whose name would have been Merope, but only six girls were actually brought home to Atlantis by Pa Salt.

In this seventh volume, the D’Aplièse sisters have decided to find Merope and invite her to join them to mark the anniversary of Pa Salt’s death. However, the only clue they have to her identity is a picture of a star-shaped emerald ring. Their search will lead them first to a vineyard in New Zealand and then right across the world to a farmhouse in West Cork, Ireland, but I can’t really say too much about who and what they discover, as to do so would risk spoiling the story and I would prefer to allow other readers to enjoy the hunt for the missing sister without knowing too much in advance.

Although I think the previous six books could probably be read in any order, I would recommend saving this one until you’ve read the others and are already familiar with the D’Aplièse sisters and their stories. All six of them have important parts to play in this book and while some of the methods they use in trying to track down Merope are a bit far-fetched and not always very kind, it was nice to see all of the sisters getting involved (with some help from other characters from earlier in the series – I particularly enjoyed meeting Star’s eccentric friend Orlando again).

The search for Merope is set in the modern day, but as some possible clues to her identity and background emerge, we also spend some time in the past, particularly in Ireland in 1920 where we follow the story of Nuala Murphy, a young woman who has joined her country’s struggle for independence. I found the historical sections of the book fascinating and completely gripping, as well as educational. For example, I knew nothing about the work of Cumann na mBan, the Irish republican women’s association who played a part in the rebellion and the subsequent civil war of 1922. It isn’t clear at first how Nuala’s story will be connected to Merope’s, but things do start to come together later in the book.

As for the overall story arc of the seven sisters, this book has left me with more questions than I started with! I’ve been forming a few theories of my own, but will have to wait for the publication of Atlas: The Story of Pa Salt for everything to be revealed.

Thanks to Macmillan for providing a copy of this book for review

Book 26/50 read for the 2021 Historical Fiction Reading Challenge.

Edited 11th June 2021: I was so sorry to hear the sad news today that Lucinda Riley has died after a four-year battle with cancer. Maybe we will never get to know Pa Salt’s secrets now, but Lucinda has left a wonderful legacy of work behind for her fans to treasure and new readers to discover.