Colon's face contorted as various emotions fought for space. Finally he managed to say, 'But... poisoned? He's got food-tasters and everything!'

'Then maybe it was one of them, Fred.'

'My gods, sir! You don't trust anyone, do you?'

'No, Fred. Incidentally, was it you? Just kidding,' Vimes added quickly as Colon's face threatened to burst into tears. 'Off you go. We don't have much time.'

Vimes shut the door and leaned on it. Then he turned the key in the lock and moved a chair under the handle.

Finally he hauled the Patrician off the floor and rolled him on to the bed. There was a grunt from the man, and his eyelids flickered.

Poison, thought Vimes. That's the worst of all. It doesn't make a noise, the poisoner can be miles away, you can't see it, often you can't really smell it or taste it, it could be anywhere - and there it is, doing its work...

The Patrician opened his eyes.

'I would like a glass of water,' he said.

There was a jug and a glass by the bed. Vimes picked up the jug, and hesitated. ‘I'll send someone to get some,' he said.

Lord Vetinari blinked, very slowly.

'Ah, Sir Samuel,' he said, 'but whom can you trust?'

There was a crowd in the big audience chamber when Vimes finally went downstairs. They were milling about, worried and unsure, and, like important men everywhere, when they were worried and unsure they got angry.

The first to bustle up to Vimes was Mr Boggis of the Guild of Thieves. 'What's going on, Vimes?' he demanded.

He met Vimes's stare. 'Sir Samuel, I mean,' he said, losing a certain amount of bustle.

'I believe Lord Vetinari has been poisoned,' said Vimes.

The background muttering stopped. Boggis realized that, since he had been the one to ask the question, he was now the man on the spot. 'Er... fatally?' he said.

In the silence, a pin would have clanged.

'Not yet,' said Vimes.

Around the hall there was a turning of heads. The focus of the universal attention was Dr Downey, head of the Guild of Assassins.

Downey nodded. 'I'm not aware of any arrangement with regard to Lord Vetinari,' he said. 'Besides, as I am sure is common knowledge, we have set the price for the Patrician at one million dollars.'

'And who has that sort of money, indeed?' said Vimes.

'Well... you for one, Sir Samuel,' said Downey. There was some nervous laughter.

'We wish to see Lord Vetinari, in any case,' said Boggis.

'No.'

'No? And why not, pray?'

'Doctor's orders.'

'Really? Which doctor?'

Behind Vimes, Sergeant Colon shut his eyes.

'Dr James Folsom,' said Vimes.

It took a few seconds before someone worked this out. 'What? You can't mean... Doughnut Jimmy? He's a horse doctor!'

'So I understand,' said Vimes.

'But why?'

'Because many of his patients survive,' said Vimes. He raised his hands as the protests grew. 'And now, gentlemen, I must leave you. Somewhere there's a poisoner. I'd like to find him before he becomes a murderer.'

He went back up the stairs, trying to ignore the shouts behind him.

'You sure about old Doughnut, sir?' said Colon, catching him up.

'Well, do you trust him?' said Vimes.

'Doughnut? Of course not!'

'Right. He's untrustworthy, and so we don't trust him. So that's all right. But I've seen him revive a horse when everyone else said it was fit only for the knackers. Horse doctors have to get results, Fred.'

And that was true enough. When a human doctor, after much bleeding and cupping, finds that a patient has died out of sheer desperation, he can always say, 'Dear me, will of the gods, that will be thirty dollars please,' and walk away a free man. This is because human beings are not, technically, worth anything. A good racehorse, on the other hand, may be worth twenty thousand dollars. A doctor who lets one hurry off too soon to that great big paddock in the sky may well expect to hear, out of some dark alley, a voice saying something on the lines of 'Mr Chrysoprase is very upset', and find the brief remainder of his life full of incident.

'No one seems to know where Captain Carrot and Angua are,' said Colon. 'It's their day off. And Nobby's nowhere to be found.'

'Well, that's something to be thankful for...'

'Bingeley bingeley bong beep,' said a voice from Vimes's pocket.

He lifted out the little organizer and raised the flap.

'Yes?'

'Er ... twelve noon,' said the imp. 'Lunch with Lady Sybil.'

It stared at their faces.

'Er ... that's all right, isn't it?' it said.

Cheery Littlebottom wiped his brow.

'Commander Vimes is right. It could be arsenic,' he said. 'It looks like arsenic poisoning to me. Look at his colour.'

'Nasty stuff,' said Doughnut Jimmy. 'Has he been eating his bedding?'

'All the sheets seem to be here, so I suppose the answer is no.'

'How's he pissing?'

'Er. The usual way, I assume.'

Doughnut sucked at his teeth. He had amazing teeth. It was the second thing everyone noticed about him. They were the colour of the inside of an unwashed teapot.

'Walk him round a bit on the loose rein,' he said.

The Patrician opened his eyes. 'You are a doctor, aren't you?' he said.

Doughnut Jimmy gave him an uncertain look. He was not used to patients who could talk. 'Well, yeah ... I have a lot of patients,' he said.

'Indeed? I have very little,' said the Patrician. He tried to lift himself off the bed, and slumped back.

‘I'll mix up a draught,' said Doughnut Jimmy, backing away. 'You're to hold his nose and pour it down his throat twice a day, right? And no oats.'

He hurried out, leaving Cheery alone with the Patrician.

Corporal Littlebottom looked around the room. Vimes hadn't given him much instruction. He'd said: 'I'm sure it won't be the food-tasters. For all they know they might be asked to eat the whole plateful. Still, we'll get Detritus to talk to them. You find out the how, right? And then leave the who to me.'

If you didn't eat or drink a poison, what else was left? Probably you could put it on a pad and make someone breathe it, or dribble some in their ear while they slept. Or they could touch it. Maybe a small dart... Or an insect bite...

The Patrician stirred, and looked at Cheery through watery red eyes. 'Tell me, young man, are you a policeman?'

'Er ... just started, sir.'

'You appear to be of the dwarf persuasion.'

Cheery didn't bother to answer. There was no use denying it. Somehow, people could tell if you were a dwarf just by looking at you.

'Arsenic is a very popular poison,' said the Patrician. 'Hundreds of uses around the home. Crushed diamonds used to be in vogue for hundreds of years, despite the fact they never worked. Giant spiders, too, for some reason. Mercury is for those with patience, aquafortis for those without. Cantharides has its followers. Much can be done with the secretions of various animals. The bodily fluids of the caterpillar of the Quantum Weather Butterfly will render a man quite, quite helpless. But we return to arsenic like an old, old friend.'

There was a drowsiness in the Patrician's voice. 'Is that not so, young Vetinari? Yes indeed, sir. Correct. But where then shall we put it, seeing that all will look for it? In the last place they will look, sir. Wrong. Foolish. We put it where no one will looked//

The voice faded to a murmur.

The bed linen, Cheery thought. Even clothes. Into the skin, slowly...

Cheery hammered on the door. A guard opened k.

'Get another bed.'

'What?'

'Another bed. From anywhere. And fresh bed linen.'

He looked down. There wasn't much of a carpet on the floor. Even so, in a bedroom, where people might walk with bare feet...