'Good.' There was a short burst of flame and rather more black smoke. 'Oh, dear,' said Leonard. The watchmen turned, like men dreading what they were about to see. The rocket had shot the length of the alley and through the window of a house. 'Ah... putting “This Way Up” on the projectile would be an important safety point to bear in mind for the new design.' said Leonard. 'Now, where's that notebook... ?'

'I think we'd better leave,' said Colon, moving backwards. 'Very fast.' Inside the house there was an explosion of stars and balls to delight young and old but not the troll who had just opened the door. 'Ah, really?' said Leonard. 'Well, if speed is required, I have this very interesting design for a two–wheeled–' Acting on an unspoken agreement, the watchmen each put a hand under a shoulder, lifted him off the ground, and ran for it.

'Oh, dear,' said Leonard, as he was dragged backwards. The watchmen dived into a side alley, and then jinked and dodged along several others with quiet professionalism. Finally they leaned Leonard against a wall and peered round the end of the alley. 'All clear,' said Nobby. 'They went the other way.'

'Right,' said Colon. 'Now, what was you doing? I mean, you might be a genius like I heard, Mister da Quirm, but when it comes to threatening people you're as clever as an inflatable dartboard.'

'I appear to have been a bit of a juggins, don't I?' Leonard agreed. 'But I do implore you to come with me. I'm afraid I thought that as warriors you would be more inclined to understand force '

'Well, yes, we're warriors,' said Sergeant Colon. 'But–'

' 'ere, have you got another one of these rockets?' said Nobby, hefting the tube onto his shoulder again. He had the special gleam in his eye that a small man gets when he's laid his hands on a big, big weapon. 'I may have,' said Leonard, and the gleam in his eye was the mad twinkle of the naturally innocent when they think they're being cunning. 'Why don't we go and see? You see, I was told to fetch you by any means necessary. 'Bribery sounds good,' said Nobby. He put his eye to the tube's sights and started making 'whoosh' noises. 'Who told you to fetch us?' said Colon. 'Lord Vetinari.'

'The Patrician wants us?'

'Yes. He said you have special qualities and must come at once.'

'To the palace? I heard he'd done a runner.'

'Oh, no. To the, er... to the, er... docks...'

'Special qualities, eh?' said Colon. 'Er, sarge...' Nobby began. 'Now then, Nobby,' said Colon importantly. 'It's about time we were given some recognition, you know that. Hexperienced officers are the backbone of the force. Seems to me,' he went on, 'seems to me that this is a case of cometh the time, cometh the man.'

'When's he cometh?'

'I'm talking about us. Men with special qualities.' Nobby nodded, but with a certain amount of reluctance. In many ways he was a much clearer thinker than his superior officer, and he was worrying about 'special qualities'. Being picked for something because of your 'special qualities' was tantamount to being volunteered. Anyway, what was so special about special qualities'? Limpets had special qualities. 'Will we go undercover again?' said Colon. Leonard blinked. 'There... yes, I think I can say there is a strong under element involved. Yes, indeed.'

'Sarge–'

'You just be quiet, corporal.' Colon pulled Nobby closer. 'Undercover means not getting stabbed and shot at, right?' he whispered. 'And what's the most important thing a professional soldier wants not to happen to him?'

'Not getting stabbed and shot,' said Nobby automatically. 'Right! So let's be going, Mr Quirm! The call has come!'

'Well done!' said Leonard. 'Tell me, sergeant, are you of a nautical persuasion?' Colon saluted again. 'Nossir! Happily married man, sir!'

'I meant, have you ploughed the ocean waves at all?' Colon gave him a cunning look. 'Ah, you can't catch me with that one, sir,' he said. 'Everyone knows the horses sink.' Leonard paused for a moment and retuned his brain to Radio Colon. 'Have you, in the past, floated around, on the sea, in a boat, at all?'

'Me, sir? Not me, sir. It's the sight of the waves going up and down, sir.'

'Really?' said Leonard. 'Well, happily, that will not be a problem.' All right, start again... Assembling facts, that's what it was about... The world watched. Someone wanted the Watch to say that the assassination had been inspired by Klatch. Who? Someone had also beheaded Snowy Slopes where he stood and left him deader than six buckets of fish bait. A vision of 71–hour Ahmed's big curved sword presented itself for his attention. So... ... let's assume that Ahmed was Khufurah's servant or bodyguard, and he'd found out... No, how could that work? Who'd tell him? Well, maybe he'd found out somehow, and that meant that he might also know who'd paid the man... Vimes sat back. It was still a mystery but he'd solve it, he knew he would. He'd assemble the facts, analyse them, look at them from every angle with an open mind, and find out exactly how Lord Rust had organized it. Rank bad hat! He didn't have to sit still for something like that, especially from a man who rhymed 'house' with 'mice'. His eye was caught by the ancient book. General Tacticus? Every kid knew about him. Ankh–Morpork had ruled a huge empire and a lot of it had been in Klatch, thanks to him. Except there wasn't any thanks for him, strangely enough. Vimes had never quite known why, but the city seemed to be rather ashamed of the general. One reason, of course, was that he'd ended up fighting Ankh–Mopork The city of Genua had run out of royalty, inbreeding having progressed to the point where the sole remaining example consisted mostly of teeth, and senior courtiers had written to Ankh–Morpork asking for help.

There'd been a lot of that sort of thing, Vimes had been surprised to learn. The little kingdoms of the Sto Plains were for ever scrounging spare royalty off one another. The King had sent Tacticus out of sheer exasperation. It's hard to run a proper empire when you're constantly getting blood–stained letters on the lines of: Dear sire, I beg to inform you that we have conquered Betrek, Smale and Ushistan. Please send AM$20,000 back pay. The man never knew when to stop. So he was hastily made a duke and packed off to Genua, whereupon his first action was to consider what was that city's greatest military threat and then, having identified it, to declare war on Ankh- Morpork. But what else had anyone expected? He'd done his duty. He'd brought back heaps of spoils, lots of captives and, almost uniquely among Ankh- Morpork's military leaders, most of his men. Vimes suspected that this last fact was one reason why history didn't approve. There was a suggestion that this was, in some way, not playing fair. 'Veni, vidi, vici.' That was what the man was supposed to have said when he'd conquered... where? Pseudopolis, wasn't it? Or Al–Khali? Or Quirm? Maybe Sto Lat? That was in the old days when you attacked anyone else's city on principle, and went back and did them over again if they looked like getting up. And in those days, you didn't care if the world watched. You wanted them to watch, and learn. 'Veni, vidi, vici.' I came, I saw, I conquered. As a comment it always struck Vimes as a bit too pat. It wasn't the sort of thing you came up with on the spur of the moment, was it? It sounded as if he had worked it out. He'd probably spent long evenings in his tent, looking up in the dictionary short words beginning with V and trying them out... Veni, vermini, vomui, I came, I got ratted, I threw up? Visi, veneri, vamoosi, I visited, I caught an embarrassing disease, I ran away? It must have been a big relief to come up with three short acceptable words. He probably made them up first, and then went off to see somewhere and conquer it. He opened the book at random. 'It is always useful to face an enemy who is prepared to die for his country,' he read. 'This means that both you and he have exactly the same aim in mind.'

'Hah!'

'Bingeley–bingeley b–' Vimes's hand slammed down on the box. 'Yes? What is it?'

'Three oh five pee em. Interview with Cpl Littlebottom re Missing Sgt: Colon,' said the demon sulkily. 'I never arranged anything like– Who told you–? Are you telling me that I've got an appointment and I don't know about it?'

'That's right.'

'So how do you know about it?'

'You told me to know about it. Last night,' said the demon. 'You can tell me about appointments I don't know about?' said Vimes.

'They're still appointments sine qua appointments,' said the demon. 'They exist, as it were, in appointment phase space.'

'What the hell does that mean?'

'Look,' said the demon patiently, 'You can have an appointment at any time, right? So therefore any appointment exists in potentia–'

'Where's that?'

'Any particular appointment simply collapses the waveform,' said the demon. 'I merely select the most likely one from the projected matrix.'

'You're just making this up,' said Vimes. 'If you were right, then any second now–' Someone knocked at the door. It was a polite, tentative tap. Vimes didn't take his eyes off the smirking demon. 'Is that you, Corporal Littlebottom?' he said. 'Yes, sir. Sergeant Colon has sent a pigeon. I thought you ought to see it, sir.'

'Come in!' A small roll of thin paper was placed on his desk. He read: Have volunteered for a mission of Vital Importance. Nobby is here also. There will be statchoos of us when this day's work is over. PS Someone I can't tell you who says this note will self–destruct in five seconds, he is sorry he hasn't got good chemicles to do it better– The paper began to crinkle around the edges and then vanished in a small puff of acrid smoke. Vimes stared at the little pile of ash that remained. 'I suppose it's a mercy they didn't blow up the pigeon, sir,' said Cheery. 'What the hell are they up to? Well, I can't chase around after them. Thanks, Cheery.' The dwarf saluted and departed. 'Co–incidence,' said Vimes. 'All right, then,' said the demon. 'Bingeley–bingeley beep! Three fifteen pee em, Emergency Meeting with Captain Carrot.' It was a cylinder, tapering to a point at both ends. At one end the taper was quite complex, the cylinder narrowing in a succession of smaller and smaller rings, overlapping one another until they ended in a large fishtail. Oiled leather could be seen gleaming in the gaps between the metal. At the other end, extending from the cylinder for all the world like the horn of a unicorn, was a very long and pointed screw thread.

The whole thing was mounted on a crude trolley, which was in turn riding on a pair of iron rails that disappeared into the black water at the far end of the boathouse. 'Looks like a giant fish to me,' said Colon. 'Made of tin.'

'With an 'orn,' said Nobby. 'It'll never float,' said Colon. 'I can see where you've gone wrong there. Everyone knows metal sinks.'

'Not entirely true,' said Leonard, diplomatically. 'In any case, this boat is designed to sink.'

'What?'

'Propulsion was a major headache, I'm afraid,' said Leonard, climbing up a stepladder. 'I thought of paddles and oars, and even some kind of screw, and then I thought: dolphins, that's the ticket! They move extremely fast with barely an effort. That's out at sea, of course, we only get the shovel– nosed dolphin in our estuary here. The linkage rods are a bit complicated but I used to be able to get quite a turn of speed. The pedalling can be somewhat tiresome, but with three of us we should be able to get up to some quite satisfactory accelerations. It's amazing what you can do when you imitate nature, I just wish my flying exp– Oh... where did you go... ?' It would be difficult to establish what part of satisfactorily accelerating nature the watchmen were trying to imitate, but it was a part which tended to get stuck in doors a lot. They stopped struggling and began to back into the room. 'Ah, sergeant,' said Lord Vetinari, entering in front of them. 'And Corporal Nobbs, too. Leonard has explained everything to you?'