I liked this one. I really enjoyed the mystery of it all. It gave me Nancy Drew vibes, and that just makes my heart happy. The back and forth storyline was great. 
I do wish there was a family tree mapped out. There are a lot of characters with multiple generations to keep track of. It's completely doable, but a quick reference would have been helpful. I also would have loved to see a map included since this was a story about a treasure hunt. It just feels like a missed opportunity.
This one has a bit of everything, and I really liked the way it wrapped up, it's fast paced and I didn't want to put it down, but I tried my best to keep with the Tandem Collective read-a-long schedule. The daily prompts to post to social media made this more fun, I love reading with others and having someone to chat with as I read.