I absolutely adored Sesame Seade, the heroine of this MG mystery, who is 11 years old, wildly precocious, self-absorbed, brilliant, and out of control. Her voice - in her narration and in her hilarious lines of dialogue - is absolutely fabulous. I loved the Cambridge University setting, too. The whole book was just enormously fun.
The only reason it's 4 stars instead of 5 stars, for me, is that I personally prefer the kind of mysteries where the stakes are personal and the detective protagonist is changed by the course of the mystery. In this one, Sesame investigates just for fun and ends the book pretty much exactly as she began - i.e., fabulous, self-confident, and with almost nothing having changed in her life. Of course, there is absolutely nothing wrong with that - Hércule Poirot and Miss Marple never change or experience personal growth in the course of any of their mysteries! there's a long tradition of mysteries where the detective is detached from the mystery and doesn't have a major character arc - it's just not *my* personally preferred type of mystery, as a reader. But I still enjoyed every page of this book, I *LOVED* Sesame, and I'd love to read the later books in the series.