By the time we reach Thud!, the City Watch has become something rather impressive. There are ranks, uniforms, procedures, paperwork and, most importantly, people who actually expect the Watch to solve crimes.

Naturally, this means things are about to get complicated.

Thud! begins with a murder that threatens to reopen one of the oldest wounds in Ankh-Morpork. The victim is a dwarf, the obvious suspects are trolls, and suddenly an ancient battle is being dragged into the present. Nobody appears particularly interested in letting old grudges remain old, especially when there are political advantages to be gained from keeping everyone angry.

Which is where Commander Vimes finds himself in trouble.

Again.

Pratchett uses the conflict between dwarfs and trolls to explore prejudice, historical memory, nationalism and the rather dangerous human habit of deciding that somebody else is the enemy. The Battle of Koom Valley has become a legend, with both sides remembering it in ways that conveniently support their own version of events.

History, it turns out, is much easier to manage when you leave out the inconvenient bits.

The social commentary is one of the strongest elements of Thud!. Pratchett is interested in how prejudice gets passed down, how political leaders can exploit fear and how communities can become trapped by stories about what happened generations ago. The dwarfs and trolls have plenty of genuine reasons to distrust each other, but the book keeps asking whether inherited hatred has to determine what happens next.

The answer is, rather obviously, no.

Unfortunately, getting people to agree on that is considerably harder.

Vimes is at the centre of all this, and Thud! continues his development from the cynical drunk we met in Guards! Guards! into someone who takes responsibility very seriously. He is still suspicious of authority, still deeply uncomfortable with being respectable and still capable of becoming terrifying when someone threatens his family or his Watch.

There is something particularly enjoyable about seeing Vimes trying to balance his responsibilities. He has a wife, a child, a household, a city to protect and a Watch full of people who occasionally seem determined to make his life more difficult.

Then there are the dwarfs.

The introduction of more detailed dwarfish culture gives the story another layer, particularly through the tensions between traditionalists and those who want to challenge old expectations. Pratchett manages to discuss identity, gender roles and cultural change without turning the book into a lecture. Instead, the ideas emerge naturally from characters who are trying to work out where they belong.

And because this is Discworld, there is plenty of comedy.

There are jokes about policing, religion, bureaucracy, archaeology, ancient grudges and the peculiar ways people justify their own behaviour. The humour is sometimes broad and sometimes so quietly buried in the prose that you realise several sentences later that you have just been ambushed by a joke.

The Watch itself remains one of my favourite parts of these books. Carrot, Angua, Detritus, Cheery and the rest have become characters rather than simply members of Vimes’s supporting cast. Their different backgrounds and personalities make the Watch feel like a genuine institution, rather than a collection of people who happen to wear the same uniform.

There is also a wonderful sense that Ankh-Morpork is changing faster than some of its citizens can cope with. The city is becoming more modern, more diverse and more interconnected, while some people are desperately trying to drag it back towards a simpler past that probably never existed.

That feels remarkably familiar.

The audiobook is another excellent reason to experience Thud!. John Culshaw handles the increasingly large cast with great confidence, giving the characters distinct voices while keeping the narration lively and conversational. He makes the Watch feel like a group of real people rather than a list of names on a page.

Peter Serafinowicz once again provides the voice of Death, who talks LIKE THIS, and gets exactly the right balance between solemnity and comedy. Bill Nighy returns as the voice of the footnotes, because apparently even the explanatory bits of Discworld need their own professional actor with more than a flair for nonchalance.

What I particularly like about Thud! is that it manages to combine a cracking mystery with some thoughtful ideas. It is about murder, ancient battles and supernatural complications, but underneath all that is a story about refusing to let hatred inherited from the past dictate the future.

Pratchett never suggests that solving these problems is easy. People are complicated, history is messy and everybody has their own version of the truth.

But somebody has to start asking the awkward questions.

Fortunately, Commander Vimes is extremely good at awkward questions.

He is less good at relaxing, but nobody is perfect.

Thud! is funny, clever, occasionally dark and another excellent step in the continuing development of the City Watch. It gives its characters room to grow while using the absurdity of Discworld to examine some real problems.

And if you happen to learn something about prejudice, history and the dangers of nationalism while laughing at homicidal dwarfs, angry trolls and a policeman who really should take a holiday, well, that is just efficient storytelling.

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