Winterhouse
Winterhouse
Ben Guterson
Chloe Bristol (illustration)

I won't go super in-depth, but for my money this was a solid book for kids. My favorite part is that the heroine is far from perfect, and sometimes says and does things she knows are crumby and doesn't quite know why she does. There are lots of word play and some light puzzles. The book does a great job of introducing a cose called the Viginere Cipher, which is a real thing and is a fantastic simple code that's very difficult to break.
We're currently reading the sequel, Secrets of Winterhouse. Too early to render any judgement but so far perhaps a little meh.