The origins of the Battle of Koom Valley between the Trolls and the Dwarves is obscure and the subject of much debate, but every year, the anniversary celebrations of the battle spark off tensions between the two communities. This year, this celebration, tensions are rising in Ank-Morpork.
Dwarf extremists are undermining (literally) the city and the Watch is starting to fall apart. When extremist leader Hamcrusher is murdered deep underground in the mines, seemingly by a Troll, Vimes must hold together the Watch; investigate the murder; prevent an outbreak of war between the Trolls and Dwarves of the city; keep the peace between Angua and a new Watch Member who just happens to be a vampire; and be home by 6.00pm every night to read "Where's My Cow?" to his young son Sam. Just to complicate matters, not only has The Patrician forced Sam to take on Sally, the vampire, he's also called in a pencil pushing bureaucrat to audit the Watch's operations. Needless to say Sam Vimes is on a pretty short fuse and it's not helped one tiny little bit when matters escalate and his own family is threatened.
In the true nature of any Terry Pratchett novel, there are more twists and turns than there are windy passages in dwarf mines in THUD!. Commander Vimes is a dedicated commander who takes his position in Ankh-Morpork very very seriously and his management of the Watch is part inspiration, part perspiration and part sheer lunacy. All the supporting cast of Watch members are here in all their assorted oddness, although, to be honest, as you read these books these characters are less odd and more realistic and endearing.
Whilst it almost seems impossible for Terry Pratchett to write a bad entry in the Discwold series, THUD! is undoubtedly one of the best books to come out of the eccentricity that is the Discworld recently.