Murder in Ankh-Morpork! Okay, that's actually not that surprising, but the victims in this case show little signs of having been dealt with by Assassins (very conscientious; they will always endeavor to clean up after themselves.) The victims are also old men, fairly harmless; there seems to be no motive. And worse, someone's poisoning the Patrician; the attempts to determine the means are driving Commander Vimes around the bend. And everyone's getting worked up about the golems in their midst: silent clay people who will do whatever they're told, and yet people fear them...
This is an interesting commentary on the worth of people, one that resonates. The Guild of Heraldry, with its multilingual puns, discovers that Nobby Nobbs is an Earl; Vimes has to deal with the increasingly multi-ethnic Watch (we're talking non-humans here); and through it all are the golems, who always work and never complain. And as always, Pratchett gives us characters who are able to demonstrate that they truly know the worth of some of their fellow residents in Ankh-Morpork. (Sometimes that worth is very small indeed.)
"That's what people say when the voiceless speak."