Snuff is the third to last Discworld novel and apparently the 8th City Watch novel though the story concentrates on Commander Sam Vimes with a few cameos from other Watchmen.

Vimes takes a vacation and with his wife Sybil, son Sam Jr, and "butler" Willikins he is determined to be bored at his estate in the country. But then he stumbles onto a crime when the other nobles try to run him out of town by framing him for a murder -- and to do that they have a goblin girl killed for the blood which is not a crime yet because goblins are not protected under the law.

It's the goblin girl's murder that spurs Sam to investigate and find murderer and trace it back to the nobles. He also gets to meet goblins and find out about their culture (which is outwardly quite disgusting to outsiders but once you get to know them still fairly disgusting but out of necessity and beliefs). I guess this is the first in-depth look at goblins (and in the next novel, Raising Steam, they're everywhere).

It's a good novel. Vimes is one of my favorite Discworld characters and although he's gotten quite powerful (both from a demon inside him and from being a duke) this is still a story where he's mostly on his own (and Willikins). And it's sad that this is it for Vimes and the Watch. (Pratchett likes his puns and Snuff refers both to the murder of the goblin girl and the tobacco product.)