The Treasury of Ankh-Morpork closed its books that year, for the first time in living memory, in the black — so far in the black, in fact, that Vetinari ordered the surplus independently audited, on the grounds that no figure produced in Ankh-Morpork had ever before erred in the city's favour, and that this was therefore the most suspicious number in its history. (It checked out. Mr Sideways had done it himself. Twice. By weight.)

The rewards were distributed in the Patrician's own fashion.

Of-the-Twilight-the-Darkness was offered a knighthood and declined it, on the grounds that goblins do not kneel, but accepted, after negotiation conducted entirely in the orientation of pots, the post of Auditor-General of Ankh-Morpork, on the understanding that the title was, as he put it, 'is now meaning what is should mean, hey,' and that he would be smelling the city's accounts annually, in person, forever.

The Golem Trust received, by Act, the thing it had wanted all along, which was nothing — no special status, no protective classification, nothing but the single line in the General Ledger, persons, full stop, which Adora Belle had framed, and hung in the Trust's office, and was seen, once, on the evening of the Act's passage, to stand in front of with a cigarette burning down unsmoked, which among Dearhearts is the equivalent of weeping at the opera.

And Mr Sideways was summoned to the Oblong Office, where the Patrician of Ankh-Morpork rose to receive him — a courtesy extended, Drumknott would later confirm, to fewer than five living persons — and invited him to name his reward. Anything. The Collector-Generalship itself, if he wished it; Mr Lipwig had recommended him for it in writing.

Mr Sideways considered the matter with the care he gave all entries.

'I should like my back-promotions, my lord,' he said. 'As froze in '73. Worked out proper, with the increments, and the interest at Treasury rate, compounded. I done the sum myself, it's all in the folder.' He laid it on the desk. 'It comes to Senior Probationary Clerk, Second Class, and forty-one dollars sixty. And a new pen. The good kind, with the brass nib. And after that, my lord, with respect, I should like to be left exactly where I am, on account of someone has to keep the books on the man who keeps the books, and I have give this matter fifty-three years of thought, and it had better be me.'

'The city,' said Lord Vetinari, signing, 'is in your debt, Mr Sideways.'

'Yes, my lord,' said Mr Sideways. 'Volume ninety-one, page twelve. I'll let you know when it's settled.'

Which left, on a fine evening in spring, Moist von Lipwig, walking to the Palace with the receipts of a grateful city in his ledgers1 and the gold suit in mothballs and the dangerous, fatal, creeping suspicion that everything was, at last, finished — and finding Lord Vetinari at the window of the Oblong Office, looking down at the city with his hands clasped behind his back, in the manner of a man listening to something underground.

'Ah, Mister Lipwig. Tell me. Are you sleeping well?'

'Like a baby, sir,' said Moist, and heard, too late, the trap close over the truth of it: he was. Eight hours a night. He had begun, the gods help him, noticing wallpaper.

'I feared as much.' Vetinari did not turn round. 'You are aware, of course, that beneath this city lies another city. And beneath that, another. The works of generations, Mister Lipwig — cisterns, culverts, conduits, the great buried plumbing of kings — all of it unmapped, unmaintained, and unowned, and all of it, I am informed by the engineers, approximately one wet spring from reminding us of its existence in the most emphatic possible terms. A million people, Mister Lipwig, and every drop they drink comes in by hope and goes out by accident. The dwarfs will not touch it, for reasons of treaty. The Guild of Plumbers and Dunnikindivers has ruled it does not exist, which I am given to understand is a professional opinion and was very expensive. It wants a man who can sell the city the thing it cannot see and will not thank him for. It wants vision. It wants nerve. It wants,' and here the Patrician turned, at last, and upon his face there was almost a quarter of a smile, 'a man who has run out of things to save.'

Far below the Palace, in the dark beneath the dark, in pipes that had not heard a footstep in three hundred years, something gurgled.

'Tell me, Mister Lipwig,' said Lord Vetinari. 'What do you know about running water?'