Gilt looked at Horsefry, and wondered whether killing him now would be the best option. Vetinari was clever. You didn’t stay ruler of a fermenting mess of a city like this one by being silly. If you saw his spy, it was a spy he wanted you to see. The way you’d know that Vetinari was keeping an eye on you would be by turning round very quickly and seeing no one at all.

Godsdamn Greenyham, too. Some people had no grasp, no grasp at all. They were so… small .

Using the clacks like that was stupid, but allowing a bottom-feeder like Horsefry to find out about it was indefensible. It was silly. Silly small people with the arrogance of kings, running their little swindles, smiling at the people they stole from, and not understanding money at all.

And stupid, pig-like Horsefry had come running here. That made it a little tricky. The door was soundproofed, the carpet was easily replaceable and, of course, Igors were renowned for their discretion, but almost certainly someone unseen had watched the man walk in and therefore it was prudent to ensure that he walked out.

‘Y’r a goo’ man, Reacher Gilt,’ Horsefry hiccuped, waving the brandy glass unsteadily now that it was almost empty again. He put it down on a small table with the exaggerated care of a drunk, but since it was the wrong one of three images of the table sliding back and forth across his vision the glass smashed on the carpet.

‘Sor’ ‘bout that,’ he slurred. ‘Y’r a goo’ man, so I’m goin’ to gi’ you this. Can’t keep it inna house, can’t keep it, not wi’ Vetininararari’s spies on to me. Can’t burn it neither, ‘sgot everything in it. All the little… transactions. Ver’ important. Can’t trust the others, they hate me. You take care of it, eh?’

He pulled out a battered red journal and proffered it unsteadily. Gilt took it, and flicked it open. His eye ran down the entries.

‘You wrote everything down, Crispin?’ he said. ‘Why?’

Crispin looked appalled. ‘Got to keep records, Reacher,’ he said. ‘Can’t cover y’tracks if you don’t know where y’left ‘em. Then… can put it all back, see, hardly a crime at all.’ He tried to tap the side of his nose, and missed.

‘I shall look after it with great care, Crispin,’ said Gilt. ‘You were very wise to bring it to me.’

‘That means a lot t’me, Reacher,’ said Crispin, now heading for the maudlin stage. ‘You take me serioussoussly, not like Greenyham and his pals. I take the risks, then they treat me like drit. I mean dirt. Bloody goo’ chap, you are. ‘sfunny, y’know, you havin’ an Igor, bloody goo’ chap like you, ‘cos—’ He belched hugely, “cos I heard that Igors only worked for mad chaps. Tot’ly bonkers chaps, y’know, and vampires and whatnot, people who’re a few pennies short of a picnic. Nothing against your man, mark you, he looks a bloody fine fellow, hahaha, several bloody fine fellows… ’

Readier Gilt pulled him up gently. ‘You’re drunk, Crispin,’ he said. ‘And too talkative. Now, what I’m going to do is call Igor—’

‘Yeth, thur?’ said Igor behind him. It was the kind of service few could afford.

‘—and he’ll take you home in my coach. Make sure you deliver him safely to his valet, Igor. Oh, and when you’ve done that could you locate my colleague Mr Gryle? Tell him I have a little errand for him. Goodnight, Crispin.’ Gilt patted the man on a wobbly cheek. ‘And don’t worry . Tomorrow you’ll find all these little anxieties will have just… disappeared.’

‘Ver’ good chap,’ Horsefry mumbled happily. ‘F’r a foreigner… ’

Igor took Crispin home. By that time the man had reached the ‘jolly drunk’ stage and was singing the kind of song that’s hilarious to rugby players and children under the age of eleven, and getting him into his house must have awoken the neighbours, especially when he kept repeating the verse about the camel.

Then Igor drove back home, put the coach away, saw to the horse, and went to the little pigeon loft behind the house. These were big, plump pigeons, not the diseased roof rats of the city, and he selected a fat one, expertly slipped a silver message ring round its leg, and tossed it up into the night.

Ankh-Morpork pigeons were quite bright, for pigeons. Stupidity had a limited life in this city. This one would soon find Mr Gryle’s rooftop lodgings, but it annoyed Igor that he never got his pigeons back.

Old envelopes rose up in drifts as Moist strode angrily, and sometimes waded angrily, through the abandoned rooms of the Post Office. He was in the mood to kick holes in walls. He was trapped. Trapped. He’d done his best, hadn’t he? Perhaps there really was a curse on this place. Groat would be a good name for it—

He pushed open a door and found himself in the big coachyard round which the Post Office was bent like the letter U. It was still in use. When the postal service had collapsed the coach part had survived, Groat had said. It was useful and established and, besides, it owned scores of horses. You couldn’t squash horses under the floor or bag them up in the attic. They had to be fed. More or less seamlessly, the coachmen had taken it over and run it as a passenger service.

Moist watched a laden coach roll out of the yard, and then movement up above caught his eye.

He had got used to the clacks towers now. Sometimes it seemed as though every roof sprouted one. Most were the new shutter boxes installed by the Grand Trunk Company, but old-fashioned arm semaphores and even signal flags were still well in evidence. Those, though, only worked slowly and by line-of-sight, and there was precious little space for that in the thrusting forest of towers. If you wanted more than the basic service, you went to one of the little clacks companies, and rented a small shutter tower with resident gargoyle to spot incoming messages and access to the bounce towers and, if you were really rich, a trained operator as well. And you paid . Moist had no grasp of or interest in technology, but as he understood it the price was something like an arm or a leg or both.

But these observations orbited his brain, as it were, like planetary thoughts around one central, solar thought: why the hell have we got a tower?

It was definitely on the roof. He could see it and he could hear the distant rattle of the shutters. And he was sure he’d seen a head, before it ducked out of sight.

Why have we got a tower up there, and who is using it?

He ran back inside. He’d never spotted a staircase to the roof, but then, who knew what was hidden behind some pile of letters at the end of some blocked corridor…

He squeezed his way along yet another passage lined with mail sacks, and came out into a space where big, bolted double doors led back to the yard. There were stairs there, leading upwards. Little safety lamps bled little pools of light into the blackness above. That was the Post Office for you, Moist thought - the Regulations said the stairs must be lit and lit they were, decades after anyone ever used them except for Stanley, the lamplighter.

There was an old freight elevator here, too, one of those dangerous ones that worked by pumping water in and out of a big rainwater tank on the roof, but he couldn’t work out how to make it go and wouldn’t have trusted it if he could. Groat had said it was broken.

At the foot of the stairs, scuffed but still recognizable, was a chalk outline. The arms and legs were not in comfortable positions.

Moist swallowed, but gripped the banister.

He climbed.

There was a door on the first floor. It opened easily. It burst open at the mere touch of the handle, spilling pent-up mail out into the stairwell like some leaping monster. Moist swayed and whimpered as the letters slithered past him, shoal after shoal, and cascaded down the stairs.

Woodenly, he climbed up another flight, and found another dimly lit door, but this time he stood to one side as he opened it. The force of the letters still rammed it against his legs, and the noise of the dead letters was a dry whispering as they poured away into the gloom. Like bats, perhaps. This whole building full of dead letters, whispering to one another in the dark as a man fell to his death—