A keeper? Oh my yes
In a fantasy story, there are certain things you can depend on. If there’s a city, it will have a Town Watch. And if there’s a Town Watch, the guards who work for it will all be incompetent. It’s more than just a convention; it’s a trope.
And Terry Pratchett never met a trope he didn’t turn upside down and shake vigorously to see what falls out, and whether the things that fall out bounce, squirm away, or sizzle quietly while melting a hole in the floor.
Guards! Guards! is one of his many romps through the great and appalling city of Ankh-Morpork – one of his early books, while he was inventing the various sub-series that make up the Discworld stories. (For those who haven’t read Pratchett – and oh what a treat you have waiting for you – most of his books are set on the Discworld. This is a flat world (as in non-spherical; it has plenty of mountains) which rests on the backs of four elephants who all stand on the back of a giant turtle that swims slowly through space. All around the Disc, the encircling ocean pours over the edge in the universe’s biggest waterfall.)
In a place like that, it’s only reasonable for magic to work. But even the Discworld isn’t magical enough to make a Noble Dragon – or, as Captain Vimes of the Night Watch puts it, “a bloody flying alligator setting fire to my city!” – plausible. Unfortunately, the dragon doesn’t care if it’s unbelievable. It just wants power and gold and lots and lots of destruction. Before long, the Patrician – the absolute ruler of Ankh-Morpork – is locked away in the dungeons he designed himself (from inside, he can hold off the world). Worse, the city has a new king, the first one in centuries, as big as a barn equipped with wings, and scales, and fire ducts somewhere way back in its nostrils. Even worse, the Librarian from Unseen University – the college of wizards – is on a rampage because somebody stole a book and because people keep calling him a monkey. Which he isn’t – he’s a full grown orangutan, thankyouverymuch.
And there’s nobody to save the city except the Night Watchmen: Captain Vimes, who has spent years emptying liquor bottles (though once the dragon turns up, he stops drinking; he doesn’t have time). Sergeant Colon, a very big man very dedicated to keeping his life peaceful, no matter how hard it is to keep from noticing crimes. Corporal Nobby Nobbs – it’s not quite clear that Nobby qualifies as human, but no other species would take him. And the newest recruit, supernaturally naive Lance-constable Carrot the six-foot-tall dwarf. (Well, dwarf by adoption.) Even with the help of Lady Sybil Rankin, probably the richest woman in the city and utterly devoted to raising little swamp dragons until they explode, will the Watch be up to the job?
Of course it will, with a little help from cunning cynicism, fanatical honesty, and True Love.