The letters burned.

Part of the ceiling fell down, showering more letters on to the flames. The fire was already reaching for the upper floors. As Stanley dragged Mr Groat across the floor another slab of plaster smashed on the tiles and the old mail that poured down after it was already burning. Smoke, thick as soup, rolled across the distant ceiling.

Stanley pulled the old man into the locker room and laid him on his bed. He rescued the golden hat, too, because Mr Lipwig would be bound to be angry if he didn’t. Then he shut the door and took down, from the shelf over Groat’s desk, the Book of Regulations. He turned the pages methodically until he came to the bookmark he’d put in a minute ago, on the page What To Do In Case Of Fire.

Stanley always followed the rules. All sorts of things could go wrong if you didn’t.

So far he’d done 1: Upon Discovery of the Fire, Remain Calm.

Now he came to 2: Shout ‘Fire!’ in a Loud, Clear Voice.

‘Fire!’ he shouted, and then ticked off 2 with his pencil.

Next was: 3: Endeavour to Extinguish Fire If Possible.

Stanley went to the door and opened it. Flames and smoke billowed in. He stared at them for a moment, shook his head, and shut the door.

Paragraph 4 said: If Trapped by Fire, Endeavour to Escape. Do Not Open Doors If Warm. Do Not Use Stairs If Burning. If No Exit Presents Itself Remain Calm and Await a) Rescue or b) Death.

This seemed to cover it. The world of pins was simple and Stanley knew his way around it as a goldfish knows its tank, but everything else was very complicated and only worked if you followed the rules.

He glanced up at the grubby little windows. They were far too small to climb through and had been welded shut by many applications of official paint, so he broke one pane as neatly as possible to allow some fresh air in. He made a note of this in the breakages book.

Mr Groat was still breathing, although with an unpleasant bubbling sound. There was a First Aid kit in the locker room, because Regulations demanded it, but it contained only a small length of bandage, a bottle of something black and sticky, and Mr Groat’s spare teeth. Mr Groat had told him never to touch his home-made medicines, and since it was not unusual for bottles to explode during the night Stanley had always observed this rule very carefully.

It did not say in the Regulations: If Attacked by Huge Swooping Screaming Creature Hit Hard in the Mouth with Sack of Pins, and Stanley wondered if he should pencil this in. But that would be Defacing Post Office Property, and he could get into trouble for that.

All avenues of further activity being therefore closed, Stanley remained calm.

It was a gentle snow of letters. Some landed still burning, fountaining out of the column of crackling fire that had already broken through the Post Office roof. Some were blackened ashes on which sparks travelled in mockery of the dying ink. Some - many - had sailed up and over the city unscathed, zigzagging down gently like communications from an excessively formal sort of god.

Moist tore off his jacket as he pushed through the crowd.

‘The people probably got out,’ said Miss Dear heart, clattering along beside him.

‘Do you really think so?’ said Moist.

‘Really? No. Not if Gilt set this up. Sorry, I’m not very good at being comforting any more.’

Moist paused, and tried to think. The flames were coming out of the roof at one end of the building. The main door and the whole left side looked untouched. But fire was sneaky stuff, he knew. It sat there and smouldered until you opened the door to see how it was getting on, and then the fire caught its breath and your eyeballs got soldered to your skull.

‘I’d better go in,’ he said. ‘Er… you wouldn’t care to say “No, no, don’t do it, you’re being far too brave!” would you?’ he added. Some people were organizing a bucket chain from a nearby fountain; it would be as effective as spitting at the sun.

Miss Dearheart caught a burning letter, lit a cigarette with it, and took a drag. ‘No, no, don’t do it, you’re being far too brave!’ she said. ‘How was that for you? But if you do, the left side looks pretty clear. Watch out, though. There are rumours Gilt employs a vampire. One of the wild ones.’

‘Ah. Fire kills them, doesn’t it?’ said Moist, desperate to look on the bright side.

‘It kills everybody, Mr Lipwig,’ said Miss Dearheart. ‘It kills everybody.’ She grabbed him by the ears and gave him a big kiss on the mouth. It was like being kissed by an ashtray, but in a good way.

‘On the whole, I’d like you to come out of there,’ she said quietly. ‘Are you sure you won’t wait? The boys will be here in a minute—’

‘The golems? It’s their day off!’

‘They have to obey their chem, though. A fire means humans are in danger. They’ll smell it and be here in minutes, believe me.’

Moist hesitated, looking at her face. And people were watching him. He couldn’t not go in there, it wouldn’t fit in with the persona. Gods damn Vetinari!

He shook his head, turned, and ran towards the doors. Best not to think about it. Best not to think about being so dumb . Just feel the front door… quite cool. Open it gently… a rush of air, but no explosion. The big hall, lit with flame… but it was all above him, and if he weaved and dodged he could make it to the door that led down to the locker room.

He kicked it open.

Stanley looked up from his stamps.

‘Hello, Mr Lipwig,’ he said. ‘I kept calm. But I think Mr Groat is ill.’

The old man was lying on the bed, and ill was too jolly a word.

‘What happened to him?’ said Moist, lifting him gently. Mr Groat was no weight at all.

‘It was like a big bird, but I frightened it off,’ said Stanley. ‘I hit it in the mouth with a sack of pins. I… had a Little Moment, sir.’

‘Well, that ought to do it,’ said Moist. ‘Now, can you follow me?’

‘I’ve got all the stamps,’ said Stanley. ‘And the cashbox. Mr Groat keeps them under his bed for safety.’ The boy beamed. ‘And your hat, too. I kept calm.’

‘Well done, well done,’ said Moist. ‘Now, stick right behind me, okay?’

‘What about Mr Tiddles, Mr Lipwig?’ said Stanley, suddenly looking worried. Somewhere outside in the hall there was a crash, and the crackle of the fire grew distinctly louder.

‘Who? Mr Tidd— the cat? To hell with—’ Moist stopped, and readjusted his mouth. ‘He’ll be outside, you can bet on it, eating a toasted rat and grinning. Come on, will you?’

‘But he’s the Post Office cat!’ said Stanley. ‘He’s never been outside!’

I’ll bet he has now, thought Moist. But there was that edge in the boy’s voice again.

‘Let’s get Mr Groat out of here, okay,’ he said, easing his way through the door with the old man in his arms, ‘and then I’ll come back for Tidd—’

A burning beam dropped on to the floor halfway across the hall, and sent sparks and burning envelopes spiralling upwards into the main blaze. It roared, a wall of flame, a fiery waterfall in reverse, up through the other floors and out through the roof. It thundered. It was fire let loose and making the most of it.

Part of Moist von Lipwig was happy to let it happen. But a new and troublesome part was thinking: I was making it work. It was all moving forward. The stamps were really working. It was as good as being a criminal without the crime. It had been fun .