As far as kids' books go, there's short and then there's movie treatment. This latest installment from Black and Clare is the latter. That's a pity because the writing retains its charm and its Underground Hogwarts with Mushrooms is full of narrative potential. Unfortunately in this installment, our hero and his friends mostly stand around passively as Bad People(tm) do Bad Things(tm) for No Particularly Good Reason(tm). 
 Like the previous two installments, our Protagonist(tm) continues to be haunted by the acts that formed him. We know this because he tells us so. In this third volume, things take on an eerie turn as his tragic History apparently Repeats Itself(tm). Sadly, that's all it does because there's no growth or change or anything despite numerous set-ups that invite that possibility. 
 Yes, this is a J and not a YA book. But J books can and often do succeed in giving their heroes an inner life, an exciting tale, and an opportunity to develop and evolve. In the Bronze Key, after 240 pages of Very Big Fonts(tm), the book suddenly stops and Bad Things(tm) happen. The end. 
 Disappointing. Book gets a two-star "It was okay" Goodreads score this time.