Due to Goodreads not allowing for half stars, I rounded this up to 4 stars though I would give it a 3.5.
Told in alternating points of view, we flash back to the 1730s in France and to the present day in France.
One of the two main characters is Sara Thomas. Sara, is in her late 20s and has Asperger's. Living in England at the time she is between jobs and her cousin Jacqui suggest that she apply herself to breaking a code found in a 18th century diary that a well renowed historian wants to use for his final book in a trilogy looking at those who lived during the Jacobite movement in France.
The second character is Mary Dundas. It is Mary's diary that Sara is trying to break. Readers find out that Mary was left to live with her aunt and uncle after her father and brothers went to live in Saint-Germain-en-Laye. One of her older brothers returns and tells Mary that he wants her to go and live with him. However, things are not what they appear and Mary is entwined in a Jacobite plot.
I wish that I liked the character of Sara as much as I did Mary. Every time the book switched to Sara's point of view I was bored unless she talked about how she figured out how to decode Mary's diary. I think that the big issue is that we don't hear much about Sara's life and how she had to deal with having Asperger's when it came to men, school, and jobs until the very end of the book. Instead we hear a little bit upfront about how Sara's cousin Jacqui has looked after her and is always there in order to calm Sara if she finds herself having a meltdown. At times I think the reader is supposed to think that Jacqui has overstepped and has kept Sara from growing. However, when you read about some of the things that Sara went through with classmates or even men she liked, I can see why Jacqui was protective. We don't hear much about Sara's parents at all and I thought that was very strange.
Mary was a living breathing person to me to the very end of this book. I found myself reading Sara's parts fast to just get back to Mary. I think that Susana Kearsley does a great deal of research for her books and it definitely shows when you read about Mary's day to day life and the adventures that happen once she goes to live with her brother.
We also get introduced to other characters in this story. I wish we had gotten more details on characters like Jacqui since she seemed to have lived a interesting life. Also I liked how in a way Jacqui was a mother to Sara. Sometimes it's not the people that give birth to you that actually step in and raise you.
We had additional characters like Luc who I just felt did not have enough details provided that I could get a handle on him. We know that Sara is attracted to him, but it baffles me a bit why he was attracted to her based on Sara's POV. I did love the character of Hugh McPherson (in Mary's POV) and I was fascinated by the details of his life and what befall those Scottish who rose up to put the "real" King back on the throne of England. I am probably going to buy a history book about the Jacobite revolution because this book just whetted my appetite a bit with all of the goings on that are mentioned.
I thought the writing was great, though I would say stiff when it came to Sara's POV (which I imagine was on purpose) and it came alive when it switched to Mary's POV. Susana Kearsley nicely adds in a side chapter heading when we switch from the contemporary timeline to the past. However, I would say that it's not even necessary because you can read the difference right away when you go from Sara to Mary and back again.
The flow was not great though. I think it's because at about the halfway mark I was sick of reading about Sara trying to decipher more code and her going on about Luc's eyes. The book came to a great big halt in my head everytime we focused on Sara after a while. I think that's because we kept leaving Mary in precarious situations. So you would end her chapters on a mini cliffhanger and then we go back to Sara talking about how Denise (she works for another woman in this story who came across this diary) telling her that she needs to take a walk or was hungry but had worked for so many hours she had forgotten to take a break. There was just no tension in the contemporary storyline at all to keep me invested.
The settings were described in pitch perfect detail. I felt like I was in France in the 1700s and in the present day. This book gave me a lot of France envy, I may need to take a trip soon.
The ending was fine with regards to Sara's story. It was Mary's story that I cared more about and I felt happy with how things were concluded. There is an afterword where Susanna Kearsley describes how she did her research and provides more details about some of the historical characters included in her book and the reappearance of some other characters from her prior works. I can't help much with that since I have not read The Firebird.