Ravingly good. I'm still smiling from finishing it, because honestly.
I loved Hazel and her friends (wonderfully written characters), but my favorite part was probably the atmosphere—I mean, just look at that cover. Very British. The story takes place in an all-girls boarding school. Daisy, the second main character, is quite posh and a little snobby and a tiny bit manipulate (although she has great character development throughout, which I loved). There's lots of British vocabulary, and lacrosse and "Etiquette" and a fancy tea shop called Willow Tea Rooms. It's very autumnal, too. Stormy November days, leaves in the spokes of a car wheel, sneaking around in dark tunnels, seances at midnight. And, of course, the murder mystery.
And it's a 5 star mystery. I'm usually able to solve these things in a middle grade story, or at least have a good hunch, but I was completely in the dark with this one. It was such fun trying to follow the clues but still be dumbfounded in the end. And the author didn't do anything silly, like making it all be a lie or giving it a super anticlimactic "you're just kids so you don't understand" ending. It was an honest-to-goodness murder, and they were honest-to-goodness pretty swell detectives.
I couldn't find a thing wrong with it. Definitely one of my favorite middle grade books of all time. I see lots of recommending in the future.