Book 15 in the Discworld series finds the guards of the Ankh-Morpork Night Watch trying to sort out an unusual set of murders. This is complicated by the impending retirement of Captain Vimes to marry Sybil Ramkin (the courtship occurred in "Guards! Guards!"), and the addition to the watch of a troll, a dwarf, and a werewolf (in the name of equal opportunity and mockery thereof). It should be noted that trolls and dwarves hate each other, and most people don't trust werewolves - even vegetarian werewolves. Gaspode the talking dog - last seen in "Moving Pictures" - and his acerbic tongue return, although Angua, the werewolf, is the only person who actually hears what he says.
The books are getting more polished as the series progresses - mostly, but not entirely, a good thing. The biggest flaw to me was that Carrot got smarter - or at least more devious. He was as dumb as a stump in his last outing, and this time around, while he remains entirely honest, he manipulates people by his implications that he might do something to them they wouldn't want (he's 6'6" and can take a troll in a fight - on the rare occasion that he threatens, people jump). This is a huge change in intelligence and a significant change in behaviour since Guards! Guards! I have mixed feelings about this: I like Carrot better in his less stupid form, but it still feels like Pratchett is cheating. Of course, all in the name of comedy - and some of it is very funny.