Nobby had been left alone for a moment while the party buzzed around him, so he'd elbowed some waiters away from the buffet and was currently scraping out a bowl with his knife.

'Ah, Lord de Nobbes,' said a voice behind him.

He turned. 'Wotcha,' he said, licking the knife and wiping it on the tablecloth.

'Are you busy, my lord?'

'Just making meself this meat-paste sandwich,' said Nobby.

That's pate de foie gras, my lord.'

S that what it's called? It doesn't have the kick of Clammer's Beefymite Spread, I know that. Want a quail's egg? They're a bit small.'

'No, thank you - '

There's loads of them,' said Nobby generously. They're free. You don't have to pay.'

'Even so - '

'I can get six in my mouth at once. Watch - '

'Amazing, my lord. I was wondering, however, whether you would care to join a few of us in the smoking-room?'

'Fghmf? Mfgmf fgmf mgghjf?'

'Indeed.' A friendly arm was put around Nobby's shoulders and he was adroitly piloted away from the buffet, but not before he had grabbed a plate of chicken legs. 'So many people want to talk to you...'

'Mgffmph?'

Sergeant Colon tried to clean himself up, but trying to clean yourself up with water from the Ankh was a difficult manoeuvre. The best you could hope for was an all-over grey.

Fred Colon hadn't reached Vimes's level of sophisticated despair. Vimes took the view that life was so full of things happening erratically in all directions that the chances of any of them making some kind of relevant sense were remote in the extreme. Colon, being by nature more optimistic and by intellect a good deal slower, was still at the Clues are Important stage.

Why had he been tied up with string? There were still loops of it around his arms and legs.

'You sure you don't know where I was?' he said.

'Yez walked into the place,' said Wee Mad Arthur, trotting along beside him. 'How come yez don't know?'

Cos it was dark and foggy and I wasn't paying attention, that's why. I was just going through the motions.'

'Aha, good one!'

'Don't mess about. Where was I?'

'Don't ask me,' said Wee Mad Arthur. 'I just hunts under the whole cattle-market area. I don't bother about what's up top. Like I said, them runs go everywhere.'

'Anyone along there make string?'

'It's all animal stuff, I tell yez. Sausages and soap and stuff like that. Is this the bit where yez gives me the money?'

Colon patted his pockets. They squelched.

'You'll have to come to the Watch House, Wee Mad Arthur.'

'I got a business to run here!'

'I'm swearin' you in as a Special Watchman for the night,' said Colon.

'What's the pay?'

'Dollar a night.'

Wee Mad Arthur's tiny eyes gleamed. They gleamed red.

'Ye gods, you look awful,' said Colon. 'What're you looking at my ear for?'

Wee Mad Arthur said nothing.

Colon turned.

A golem was standing behind him. It was taller than any he'd seen before, and much better proportioned - a human statue rather than the gross shape of the usual golems, and handsome, too, in the cold way of a statue. And its eyes shone like red searchlights.

It raised a fist above its head and opened its mouth. More red light streamed out.

It screamed like a bull.

Wee Mad Arthur kicked Colon on the ankle.

'Are we running or what?' he said.

Colon backed away, still staring at the thing.

'It's... it's all right, they can't move fast...'he muttered. And then his sensible body gave up on his stupid brain and fired up his legs, spinning him around and shoving him in the opposite direction.

He risked looking over his shoulder. The golem was running after him in long, easy strides.

Wee Mad Arthur caught him up.

Colon was used to proceeding gently. He wasn't built for high speeds, and said so. 'And you certainly can't run faster than that thing!' he wheezed.

'Just so long as I can run faster'n yez,' said Wee Mad Arthur. This way!'

There was a flight of old wooden stairs against the side of a warehouse. The gnome went up them like the rats he hunted. Colon, panting like a steam engine, followed him.

He stopped half-way up and looked around.

The golem had reached the bottom step. It tested it carefully. The wood creaked and the whole stairway, grey with age, trembled.

'It won't take the weight!' said Wee Mad Arthur. 'The bugger's gonna smash it up! Yeah!'

The golem took another step. The wood groaned.

Colon got a grip on himself and hurried on up the stairs.

Behind him, the golem seemed to have satisfied itself that the wood could indeed take its weight, and started to leap from step to step. The rails shook under Colon's hands and the whole structure swayed.

'Come on, will yez?' said Wee Mad Arthur, who had already reached the top. 'It's gaining on yez!'

The golem lunged. The stairs gave way. Colon flung out his hands and grabbed the edge of the roof. Then his body thudded into the side of the building.

There was the distant sound of woodwork hitting cobbles.

'Come on then,' said Wee Mad Arthur. 'Pull yourself up, yer silly bugger!' 'Can't,' said Colon. 'Why not?' 'It's holding on to my foot...'

'A cigar, your lordship?'

'Brandy, my lord?'

Lord de Nobbes sat back in the comfort of his chair. His feet only just reached the ground. Brandy and cigars, eh? This was the life all right. He took a deep puff at the cigar.

'We were just talking, my lord, about the future governance of the city now that poor Lord Vetinari's health is so bad...'

Nobby nodded. This was the kind of thing you talked about when you were a nob. This was what he'd been born for.

The brandy was giving him a pleasant warm feeling.

'It would obviously upset the current equilibrium if we looked for a new Patrician at this point,' said another armchair. 'What is your view, Lord de Nobbes?'

'Oh, yeah. Right. The guilds'd fight like cats in a sack,' said Nobby. 'Everyone knows that.'

'A masterly summary, if I may say so.'

There was a general murmur of agreement from the other chairs.

Nobby grinned. Oh, yes. This was the bee's pyjamas and no mistake. Hobnobbing with his fellow nobs, talking big talk about important matters instead of having to think up reasons why the tea-money tin was empty... oh, yes.

A chair said, 'Besides, are any of the guild leaders up to the task? Oh, they can organize a bunch of tradesmen, but ruling an entire city ... I think not. Gentlemen, perhaps it is time for a new direction. Perhaps it is time for blood to reveal itself.'

Odd way of putting it, Nobby thought, but clearly this was how you were supposed to speak.

'At a time like this,' said a chair, 'the city will surely look at those representatives of its most venerable families. It would be in all our interests if such a one would take up the burden.'

'He'd need his head examined, if you want my opinion,' said Nobby. He took another swig of the brandy and waved the cigar expansively.

'Still, not to worry,' he said. 'Everyone knows we've got a king hanging around. No problem there. Send for Captain Carrot, that's my advice.'

Another evening folded over the city in layers of fog.

When Carrot arrived back at the Watch House Corporal Littlebottom made a face at him and indicated, with a flicker of her eyes, the three people sitting grimly on the bench against one wall.

They want to see an officer!' she hissed. 'But S'arnt Colon isn't back and I knocked on Mr Vimes's door and I don't think he's in.'

Carrot composed his features into a welcoming smile.

'Mrs Palm, he said. 'And Mr Boggis... and Dr Downey. I am so sorry. We're rather stretched at present, what with the poisoning and this business with the golems - '

The head of the Assassins' Guild smiled, but only with his mouth. 'It's about the poisoning we wish to speak,' he said. 'Is there somewhere a little less public?'

'Well, there's the canteen,' said Carrot. 'It'll be empty at this time of night. If you'd just step this way...'

'You do well for yourselves here, I must say,' said Mrs Palm. 'A canteen - '

She stopped as she stepped through the door.

'People eat in here?' she said.

'Well, grumble about the coffee, mostly,' said Carrot. 'And write their reports. Commander Vimes is keen on reports.'

'Captain Carrot,' said Dr Downey, firmly, 'we have to talk to you on a grave matter concerning -  What have I sat in?'

Carrot brushed a chair hurriedly. 'Sorry, sir, we don't seem to have much time to clean up - '

'Leave it for now, leave it for now.'

The head of the Assassins' Guild leaned forward with his hands pressed together.

'Captain Carrot, we are here to discuss this terrible matter of the poisoning of Lord Vetinari.'

'You really ought to talk to Commander Vimes - '

'I believe that on a number of occasions Commander Vimes has made derogatory comments to you about Lord Vetinari,' said Dr Downey.

'You mean like He ought to be hung except they can't find a twisty enough rope ?' said Carrot. 'Oh, yes. But everyone does that.'

'Do you?'

'Well, no,' Carrot admitted.

'And I believe he personally took over the investigation of the poisoning?'

'Well, yes. But - '

'Didn't you think that was odd?'

'No, sir. Not when I thought about it. I think he's got a sort of soft spot for the Patrician, in his way. He once said that if anyone was going to kill Vetinari he'd like it to be him.'

'Indeed?'

'But he was smiling when he said it. Sort of smiling, anyway.'

'He, er, visits his lordship most days, I believe?'

'Yes, sir.'

'And I understand that his efforts to discover the poisoner have not reached any conclusions?'

'Not as such, sir,' said Carrot. 'We've found a lot of ways he's not being poisoned.'

Downey nodded at the others. 'We would like to inspect the Commander's office,' he said.

'I don't know if that's - ' Carrot began.

'Please think very carefully,' said Dr Downey. 'We three represent most of the guilds of this city. We feel we have a good reason for inspecting the Commander's office. You will of course accompany us to see that we do nothing illegal.'

Carrot looked awkward. 'I suppose ... if I'm with you...' he said.

'That's right,' said Downey. 'That makes it official.'

Carrot led the way. 'I don't even know if he's back,' he said, opening the door. 'As I said, we've been... oh.'

Downey peered around him and at the figure slumped over the desk.

'It would appear that Sir Samuel is in,' he said. 'But quite out of it.'

'I can smell the drink from here,' said Mrs Palm. 'It's terrible what drink will do to a man.'

'A whole bottle of Bearhugger's finest,' said Mr Boggis. 'All right for some, eh?'

'But he hasn't touched a drop all year!' said Carrot, giving the recumbent Vimes a shake. 'He goes to meetings about it and everything!'

'Now let us see...' said Downey.

He pulled open one of the desk drawers.

'Captain Carrot?' he said. 'Can you witness that there appears to be a bag of greyish powder in here? I will now - '

Vimes's hand shot out and slammed the drawer on the man's fingers. His elbow rammed back into the assassin's stomach and, as Downey's chin jerked down, Vimes's forearm swung upwards and caught him full on the nose.

Then Vimes opened his eyes.

'Wassat? Wassat?' he said, raising his head. 'Dr Downey? Mr Boggis? Carrot? Hmm?'

'Hwat? Hwat?' screamed Downey. 'You hnsfruck me!'

'Oh, I'm so sorry,' said Vimes, concern radiating from every feature as he pushed the chair back into Downey's groin and stood up. 'I'm afraid I must have dropped off and, of course, when I woke up and found someone stealing from...'

'You're raving drunk, man!' said Mr Boggis.

Vimes's features froze.

'Indeed? Peter Piper picked a peck of pickled peppers,' he snarled, prodding the man in the chest. 'A peck of bloody pickled peppers Peter Piper damn well picked. Do you want me to continue?' he said, poking the man until his back was against the wall. 'It doesn't get much better!'

'Hwhat about thif packet?' shouted Downey, clutching his streaming nose with one hand and waving at the desk with the other.

Vimes still wore a wild-eyed mirthless grin. 'Ah, well, yes,' he said. 'You've got me there. A highly dangerous substance.'

'Ah, you admit it!'

'Yes, indeed. I suppose I have no alternative but to dispose of the evidence...' Vimes grabbed the packet, ripped it open and tipped most of the powder into his mouth.

'Mmm mmm,' he said, powder spraying everywhere as he masticated. 'Feel that tingle on the tongue!'

'But that's arsenic,' said Boggis.

'Good gods, is it?' said Vimes, swallowing. 'Amazing! I've got this dwarf downstairs, you know, clever little bugger, spends all his time with pipes and chemicals and things to find out what is arsenic and what isn't, and all the time here's you able to spot it just by looking! I've got to hand it to you!'

He dropped the torn packet into Boggis's hand, but the thief jerked back and the packet tumbled to the floor, spraying its contents.

'Excuse me,' said Carrot. He knelt down and peered at the powder.

It is traditionally the belief of policemen that they can tell what a substance is by sniffing it and then gingerly tasting it, but this practice had ceased in the Watch ever since Constable Flint had dipped his finger into a blackmarket consignment of ammonium chloride cut with radium, said 'Yes, this is definitely slab wurble wurble sclup , and had to spend three days tied to his bed until the spiders went away.

Nevertheless, Carrot said, 'I'm sure this isn't poisonous,' licked his finger and tried a bit.

'It's sugar,' he said.

Downey, his composure severely compromised, waved a finger at Vimes. 'You admitted it was dangerous!' he screamed.

'Right! Take too much of it and see what it does to your teeth!' bellowed Vimes. 'What did you think it was?'

'We had information...' Boggis began.

'Oh, you had information, did you?' said Vimes.

'You hear that, Captain? They had information. So that's all right!'

'We acted in good faith,' said Boggis.

'Let me see,' said Vimes. 'Your information was something on the lines of: Vimes is dead drunk in the Watch House and he's got a bag of arsenic in his desk? And I'll just bet you wanted to act in good faith, eh?'

Mrs Palm cleared her throat. 'This has gone far enough. You are correct, Sir Samuel,' she said. 'We were all sent a note.' She handed a slip of paper to Vimes. It had been written in capitals. 'And I can see we have been misinformed,' she added, glaring at Boggis and Downey. 'Do allow me to apologize. Come, gentlemen.'

She swept out of the door. Boggis followed her quickly.

Downey dabbed at his nose. 'What's the guild price on your head, Sir Samuel?' he said.

'Twenty thousand dollars.'

'Really? I think we shall definitely have to upgrade you.'

'Delighted. I shall have to buy a new beartrap.'

'I'll, er, show you out,' said Carrot.

When he hurried back he found Vimes leaning out of the window and feeling the wall below it.

'Not a brick dislodged,' Vimes muttered. 'Not a tile loose... and the front office has been manned all day. Odd, that.'

He shrugged and walked back to his desk, where he picked up the note.

'And I shouldn't think we'll be able to find any Clues on this,' he said. 'There's too many greasy fingermarks all over it.' He put down the paper and glared at Carrot. 'When we find the man responsible,' he said, 'somewhere at the top of the charge sheet is going to be Forcing Commander Vimes to Tip a Whole Bottle of Single Malt on to the Carpet. That's a hanging offence.' He shuddered. There were some things a man should not have to do.

'It's disgusting!' said Carrot. 'Fancy them even thinking that you'd poison the Patrician!'

'I'm offended that they think I'd be daft enough to keep the poison in my desk drawer,' said Vimes, lighting a cigar.

'Right,' said Carrot. 'Did they think you were some kind of fool who'd keep evidence like that where anyone could find it?'

'Exactly,' said Vimes, leaning back. 'That's why I've got it in my pocket.'

He put his feet on the desk and blew out a cloud of smoke. He'd have to get rid of the carpet. He wasn't going to spend the rest of his life working in a room haunted by the smell of departed spirits.

Carrot's mouth was still open.

'Oh, good grief,' said Vimes. 'Look, it's quite simple, man. I was expected to go At last, alcohol! , and chugalug the lot without thinking. Then some respectable pillars of the community' - he removed the cigar from his mouth and spat -'were going to find me, in your presence, too -which was a nice touch - with the evidence of my crime neatly hidden but not so well hidden that they couldn't find it.' He shook his head sadly. 'The trouble is, you know, that once the taste's got you it never lets go.'

'But you've been very good, sir,' said Carrot. 'I've not seen you touch a drop for - '

'Oh, that,' said Vimes. 'I was talking about policing, not alcohol. There's lots of people will help you with the alcohol business, but there's no one out there arranging little meetings where you can stand up and say, My name is Sam and I'm a really suspicious bastard. '

He pulled a paper bag out of his pocket. 'We'll get Littlebottom to have a look at this,' he said. 'I damn sure wasn't going to try tasting it. So I nipped down to the canteen and filled a bag with sugar out of the bowl. It was but the work of a moment to fish Nobby's butts out of it, I might add.' He opened the door, poked his head out into the corridor and yelled, 'Littlebottom!' To Carrot he added, 'You know, I feel quite perked up. The old brain has begun to work at last. You know the golem that did the killing?'

'Yes, sir?'

'Ah, but do you know what was special about it?'

'Can't think, sir,' said Carrot, 'except that it was a new one. The golems made it themselves, I think. But of course they needed a priest for the words and they had to borrow Mr Hopkinson's oven. I expect the old men thought it would be interesting. They were historians, after all.'

It was Vimes's turn to stand there with his mouth open.

Finally he got control of himself. 'Yes, yes, of course,' he said, his voice barely shaking. 'Yes, I mean, that's obvious. Plain as the nose on your face. But... er, have you worked out what else is special about k?' he added, trying to keep any trace of hope out of his voice.

'You mean the fact it's gone mad, sir?'

'Well, I didn't think it was winner of the Ankh-Morpork Mr Sanity Award!' said Vimes.

'I mean they drove it mad, sir. The other golems. They didn't mean to, but it was built-in, sir. They wanted it to do so many things. It was like their... child, I think. All their hopes and dreams. Arid when they found out it'd been killing people... well, that's terrible to a golem. They mustn't kill, and it was their own day doing it - '

'It's not a great idea for people, either.'

'But they'd put all their future in it - '

'You wanted me, Commander?' said Cheery.

'Oh, yes. Is this arsenic?' said Vimes, handing her the packet.

Cheery sniffed at it. 'It could be arsenous acid, sir. I'll have to test it, of course.'

'I thought acids sloshed about in jars,' said Vimes. 'Er ... what's that on your hands?'

'Nail varnish, sir.'

'Nail varnish?'

'Yes, sir.'

'Er... fine, fine. Funny, I thought it would be green.'

'Wouldn't look good on the fingers, sir.'

'I meant the arsenic, Littlebottom.'

'Oh, you can get all sorts of colours of arsenic, sir. The sulphides - that's the ores, sir - can be red or brown or yellow or grey, sir. And then you cook them up with nitre and you get arsenous acid, sir. And a load of nasty smoke, really bad.'

'Dangerous stuff,' said Vimes.

'Not good at all, sir. But useful, sir,' said Cheery. 'Tanners, dyers, painters... It's not just poisoners that've got a use for arsenic.'

'I'm surprised people aren't dropping dead of it all the time,' said Vimes.

'Oh, most of them use golems, sir - '

The words stayed in the air even after Cheery stopped speaking.

Vimes caught Carrot's eye and started to whistle hoarsely under his breath. This is it, he thought. This is where we've filled ourselves up with so many questions that they're starting to overflow and become answers.

He felt more alive than he had for days. The recent excitement still tingled in his veins, kicking his brain into life. It was the sparkle you got with exhaustion, he knew. You were so bone-weary that a shot of adrenalin hit you like a falling troll. They must have it all now. All the bits. The edges, the corners, the whole picture. All there, just waiting to be pieced together...

'These golems,' said Carrot. 'They'd be covered in arsenic, would they?'

'Could be, sir. I saw one at the Alchemists' Guild building in Quirm and, hah, it'd even got arsenic plated on its hands, sir, on account of stirring crucibles with its fingers...'

'They don't feel heat/ said Vimes.

'Or pain,' said Carrot.

'That's right,' said Cheery. She looked uncertainly from one to the other.

'You can't poison them,' said Vimes.

'And they'll obey orders,' said Carrot. 'Without speaking.'

'Golems do all the really mucky jobs,' said Vimes.

'You could have mentioned this before, Cheery,' said Carrot.

'Well, you know, sir ... Golems are just there, sir. No one notices golems.'

'Grease under his fingernails,' said Vimes, to the room in general. 'The old man scratched at his murderer. Grease under his fingernails. With arsenic in it.'

He looked down at the notebook, still on his desk. It's there, he thought. Something we haven't seen. But we've looked everywhere. So we've seen the answer and haven't seen that it is the answer. And if we don't see it now, at this moment, we'll never see it at all...

'No offence, sir, but that's probably not a help,' said Cheery's voice somewhere in the distance. 'So many of the trades that use arsenic involve some kind of grease.'

Something we don't see, thought Vimes. Something invisible. No, it wouldn't have to be invisible. Something we don't see because it's always there. Something that strikes in the night...

And there it was.

He blinked. The glittering stars of exhaustion were causing his mind to think oddly. Well, thinking rationally hadn't worked.

'No one move,' he said. He held up a hand for silence. There it is,' he said softly. There. On my desk. You see it?'

'What, sir?' said Carrot.

'You mean you haven't worked it out?' said Vimes.

'What, sir?'

'The thing that's poisoning his lordship. There it is ... on the desk. See?'

'Your notebook?'

'No!'

'He drinks Bearhugger's whisky?' said Cheery.

'I doubt it,' said Vimes.

'The blotter?' said Carrot. 'Poisoned pens? A packet of Pantweeds?'

'Where're they?' said Vimes, patting his pockets.

'Just sticking out from under the letters in the In Tray, sir,' said Carrot. He added reproachfully, 'You know, sir, the ones you don't answer.'

Vimes picked up the packet and extracted another cigar. Thanks,' he said. 'Hah! I didn't ask Mildred Easy what else she took! But of course they're a servant's little bonus, too! And old Mrs Easy was a seamstress, a proper seamstress! And this is autumn! Killed by the nights drawing in! See?'

Carrot crouched down and looked at the surface of the desk. 'Can't see it myself, sir,' he said.

'Of course you can't,' said Vimes. 'Because there's nothing to see. You can't see it. That's how you can tell it's there. If it wasn't there you'd soon see it!' He gave a huge manic grin. 'Only you wouldn't! See?'

'You all right, sir?' said Carrot. 'I know you've been overdoing it a bit these last few days - '

'I've been underdoing it!' said Vimes. 'I've been running around looking for damn Clues instead of just thinking for five minutes! What is it I'm always telling you?'

'Er ... er ... Never trust anybody, sir?'

'No, not that.'

'Er ... er ... Everyone's guilty of something, sir?'

'Not that, either.'

'Er ... er ... Just because someone's a member of an ethnic minority doesn't mean they're not a nasty small-minded little jerk, sir?'

'N -  When did I say that?'

'Last week, sir. After we'd had that visit from the Campaign for Equal Heights, sir.'

Well, not that. I mean... I'm pretty sure I'm always saying something else that's very relevant here. Something pithy about police work.'

'Can't remember anything right now, sir.'

'Well, I'll damn well make up something and start saying it a lot from now on.'

'Jolly good, sir.' Carrot beamed. 'It's good to see you're your old self again, sir. Looking forward to kicking ar - to prodding buttock, sir. Er... What have we found, sir?'

'You'll see! We're going to the palace. Fetch Angua. We might need her. And bring the search warrant.'

'You mean the sledgehammer, sir?'

'Yes. And Sergeant Colon, too.'

'He hasn't signed in again yet, sir,' said Cheery. 'He should have gone off-duty an hour ago.'

'Probably hanging around somewhere, staying out of trouble,' said Vimes.

Wee Mad Arthur peered over the edge of the wall. Somewhere below Colon, two red eyes stared up at him.

'Heavy, is it?'

S!'

'Kick it with your other foot!'

There was a sucking sound. Colon winced. Then there was a plop, a moment of silence, and a loud crash of pottery down in the street.