This may be my favourite novel out of Pullman's entire body of work. It certainly engaged me at a level I have not felt since I first read The Golden Compass (/Northern Lights), and while that struck me as a wonderful book for young adults (and I have reread it several times long past my own youth), it always had an air of the Manichean simplicity that children's literature is often disparaged for exhibiting. The Secret Commonwealth does not simplify anything - in fact it takes all that was wonderful about the other books in the series and elaborates and questions every assumption those worlds created. There is something of Graham Greene here - the moral complexity and unsolvable difficulties of adulthood, mixed with a bit of intrigue and spectacular characterisation. Pullman takes Lyra, Malcolm, and others on a complex journey that kept me enraptured from the beginning through all seven hundred pages, and left me wishing for more. My only complaint is that the conclusion suffers from that malady that all excellent books in a series exhibit - it left me hungering for the sequel.