And then, just when you thought it was as bad as it could be, up popped Grag Hamcrusher and his chums. Deep-downers, they were called, dwarfs as fundamental as the bedrock. They'd turned up a month ago, occupied some old house in Treacle Street and had hired a bunch of local lads to open up the basements. They were grags'. Vimes knew just enough dwarfish to know that grag meant renowned master of dwarfish lore. Hamcrusher, however, had mastered it in his own special way. He preached the superiority of dwarf over troll, and that the duty of every dwarf was to follow in the footsteps of their forefathers and remove trollkind from the face of the world. It was written in some holy book, apparently, so that made it okay, and probably compulsory.

Young dwarfs listened to him, because he talked about history and destiny and all the other words that always got trotted out to put a gloss on slaughter. It was heady stuff, except that brains weren't involved. Malign idiots like him were the reason you saw dwarfs walking around now not just with the `cultural' battle-axe but heavy mail, chains, morningstars, broadswords ... all the dumb, in-your-face swaggering that was known as `clang.

Trolls listened too. You saw more lichen, more clan graffiti, more body-carving and much, much bigger clubs being dragged around.

It hadn't always been like this. Things had loosened up a lot in the last ten years or so. Dwarfs and trolls as races would never be chums, but the city stirred them together and it had seemed to Vimes that they had managed to get along with no more than surface abrasions.

Now the melting pot was full of lumps again.

Gods damn Hamcrusher. Vimes itched to arrest him. Technically, he was doing nothing wrong, but that was no barrier to a copper who knew his business. He could certainly get him under Behaviour Likely To Cause A Breach Of The Peace. Vetinari had been against it, though. He'd said it'd only inflame the situation, but how much worse could it get?

Vimes closed his eyes and recalled that little figure, dressed in heavy black leather robes and hooded so that he would not commit the crime of seeing daylight. A little figure, but with big words. He remembered:

`Beware of the troll. Trust him not. Turn him from your door. He is nothing, a mere accident of forces, unwritten, unclean, the mineral world's pale, jealous echo of living, thinking creatures. In his head, a rock; in his heart, a stone. He does not build, he does not delve, he neither plants nor harvests. His nascency was a deed of theft and everywhere he drags his club he steals. When not thieving, he plans theft. The only purpose in his miserable life is its ending, relieving from the wretched rock his all-too-heavy burden of thought. I say this in sadness. To kill the troll is no murder. At its very worst, it is an act of charity.'

It was round about that time that the mob had broken into the hall.

That was how much worse it could be. Vimes blinked at the newspaper again, this time seeking anything that dared suggest that people in Ankh-Morpork still lived in the real world

'Oh, damn!' He got up and hurried down the stairs, where Cheery practically cowered at his thundering approach.

`Did we know about this?' he demanded, thumping the paper down on the Occurrences Ledger.

`Know about what, sir?' said Cheery.

Vimes prodded a short illustrated article on page four, his finger stabbing at the page. `See that?' he growled. `That pea-brained idiot at the Post Office has only gone and issued a Koom Valley stamp!'

The dwarf looked nervously at the article. `Er ... two stamps, sir,' she said.

Vimes looked closer. He hadn't taken in much of the detail before the red mist descended. Oh yes, two stamps. They were very nearly identical. They both showed Koom Valley, a rocky area ringed by mountains. They both showed the battle. But in one, little figures of trolls were pursuing dwarfs from right to left, and, in the other, dwarfs were chasing trolls from left to right. Koom Valley, where the trolls ambushed the dwarfs and the dwarfs ambushed the trolls. Vimes groaned. Pick your own stupid history, a snip at ten pence, highly collectable.

`The Koom Valley Memorial Issue,' he read. `But we don't want them to remember it! We want them to forget it!'

`It's only stamps, sir,' said Cheery. `I mean, there's no law against stamps. ..'

`There ought to be one against being a bloody fool!'

`If there was, sir, we'd be on overtime every day!' said Cheery, grinning.

Vimes relaxed a little. `Yep, and no one could build cells fast enough. Remember the cabbage-scented stamp last month?

"Send your expatriate sons and daughters the familiar odour of home"? They actually caught fire if you put too many of them together!'

`I still can't get the smell off my clothes, sir.'

`There are people living a hundred miles away who can't, I reckon. What did we do with the bloody things in the end?'

`I put them in No. 4 evidence locker and left the key in the lock,' said Cheery.

`But Nobby Nobbs always steals anything that-' Vimes began.

`That's right, sir!' said Cheery happily. `I haven't seen them for weeks.'

There was a crash from the direction of the canteen, followed by shouting. Something in Vimes, perhaps the very part of him that had been waiting for the first shoe, propelled him across the office, down the passage and to the canteen's doorway at a speed that left dust spiralling on the floor.

What met his eyes was a tableau in various shades of guilt. One of the trestle tables had been knocked over. Food and cheap tinware was strewn across the floor. On one side of the mess was troll Constable Mica, currently being held between troll Constables Bluejohn and Schist; on the other was dwarf Constable Brakenshield, currently being lifted off the ground by probably human Corporal Nobbs and definitely human Constable Haddock.

There were watchmen at the other tables too, all caught in the act of rising. And, in the silence, audible only to the fine-tuned ears of a man searching for it, was the sound of hands pausing an inch away from the weapon of choice, and very slowly being lowered.

`All right,' said Vimes, in the ringing vacuum. `Who's going to be the first to tell me a huge whopper? Corporal Nobbs?'

`Well, Mister Vimes,' said Nobby Nobbs, lowering the mute Brakenshield to the floor,'. .. er ... Brakenshield here ... picked up Mica's ... yes, picked up Mica's mug by mistake, as it were ... and

... we all spotted that and jumped up, yes. .: Nobby speeded up, the really steep fibs now successfully negotiated,'. .. and that's how the table got knocked over ... 'cos,' and here Nobby's face assumed an expression of virtuous imbecility that was really quite frightening to see, `he'd have really hurt himself if he'd taken a swig of troll coffee, sir.'

Inside, Vimes sighed. As stupid lame excuses went, it wasn't actually a bad one. For one thing it had the virtue of being completely unbelievable. No dwarf would come close to picking up a mug of troll espresso, which was a molten chemical stew with rust sprinkled on the top. Everyone knew this, just as everyone knew that Vimes could see that Brakenshield was holding an axe over his head and Constable Bluejohn was still frozen in the act of wrenching a club off Mica. And everyone knew, too, that Vimes was in the mood to sack the first bloody idiot to make a wrong move and, probably, anyone standing near him.

`That's what it was, was it?' said Vimes. `So it wasn't, as it might be, someone making a nasty remark about a fellow officer and others of his race, perhaps? Some little bit of stupidity to add to the mess of it that's floating around the streets right now?'

`Oh, nothing like that, sir,' said Nobby. `Just one of them ... things.