I was utterly gripped by this book. It's hard to talk about the plot very much without giving spoilers, but there are two main focuses of the book: a sci-fi mystery that is tense and at times creepy, and a human story about Maisie's life and her relationships with her family, especially her sister Lily, that gets quite emotional at times. I loved both of these equally. 

There is a lot of science in the book. Scientific theories are explained on a regular basis, albeit in very simplistic terms. For some readers there may be too much of this, but I quite enjoyed it. 

For a lot of the book you don't know what is going on, and I came up with any number of possible explanations in my head. I have to admit that when the reveal came, I felt a little let down, but I loved the final chapter, so I think on reflection I'm happy with it. 

Overall an impressive book, and I very much want to read more from this author.