I don't really understand the near-universal admiration for Roger Zelazny. The conceit of this book was cute, but the actual execution was wildly frustrated. So many secrets are being kept from the reader only to be revealed as trivial. The Things in the Mirror, the Thing in the Attic--they turned out to be noThingburgers, entirely failing to live up to their setup, while the unexpected rule about the location of the sacrifice came out of nowhere--fully adhoc, entirely not set up at all. The Great Detective's eventual role, given how important a role he'd been set up to play, was disappointing (outshadowed by a rat, I say!), and in the end it felt like an exercise in plot design, rather than a fully fledged book with characters and proper emotional stakes. 

I did like the howlable moon, though. That was a good line. 

Also once again we have the token lady amidst all the dudes, and the sacrifice is, of course, the helpless girl.