'What, that it's all settled?' said Cuddy. 'Oh, yeah. We might as well be off. OK, Detritus?'

Detritus was staring moodily at nothing with his knuckles resting on the ground. This was a normal stance for a troll while waiting for the next thought to arrive.

The syllables of his name kicked a neuron into fitful activity.

'What?' he said.

'It's all settled.'

'What is?'

'You know – Mr Hammerhock's death and everything.'

'Is it?'

'Yes!'

'Oh.'

Detritus considered this for a while, nodded, and settled back into whatever state of mind he normally occupied.

Another neuron gave a fizzle.

'Right,' he said.

Cuddy watched him for a moment.

'That's about it,' he said, sadly. 'That's all we're getting.'

'I'll be back shortly,' said Carrot. 'Shall we be off . . . Joey, wasn't it? Dr Whiteface?'

'I suppose there's no harm,' said Dr Whiteface. 'Very well. Show Corporal Carrot anything he likes, Boffo.'

'Right, sir,' said the little clown.

'It must be a jolly job, being a clown,' said Carrot.

'Must it?'

'Lots of japes and jokes, I mean.'

Boffo gave Carrot a lopsided look.

'Well . . .' he said. 'It has its moments . . .'

'I bet it does. I bet it does.'

'Are you often on gate duty, Boffo?' said Carrot pleasantly, as they strolled through the Fools' Guild.

'Huh! Just about all the time,' said Boffo.

'So when did that friend of his, you know, the Assassin . . . visit him?'

'Oh, you know about him, then,' said Boffo.

'Oh, yes,' said Carrot.

'About ten days ago,' said Boffo. 'It's through here, past the pie range.'

'He'd forgotten Beano's name, but he did know the room. He didn't know the number but he went straight to it,' Carrot went on.

'That's right. I expect Dr Whiteface told you,' said Boffo.

'I've spoken to Dr Whiteface,' said Carrot.

Angua felt she was beginning to understand the way Carrot asked questions. He asked them by not asking them. He simply told people what he thought or suspected, and they found themselves filling in the details in an attempt to keep up. And he never, actually, told lies.

Boffo pushed open a door and fussed around lighting a candle.

'Here we are then,' he said. 'I'm in charge of this, when I'm not on the bloody gate.'

'Ye gods,' said Angua, under her breath. 'It's horrible.'

'It's very interesting,' said Carrot.

'It's historical,' said Boffo the clown.

All those little heads . . .'

They stretched away in the candlelight, shelf on shelf of them, tiny little clown faces – as if a tribe of head-hunters had suddenly developed a sophisticated sense of humour and a desire to make the world a better place.

'Eggs,' said Carrot. 'Ordinary hens' eggs. What you do is, you get a hen's egg, and you make a hole in either end and you blow the egg stuff out, and then a clown paints his make-up on the egg and that's his official make-up and no other clown can use it. That's very important. Some faces have been in the same family for generations, you know. Very valuable thing, a clown's face. Isn't that so, Boffo?'

The clown was staring at him.

'How do you know all that?'

'I read it in a book.'

Angua picked up an ancient egg. There was a label attached to it, and on the label were a dozen names, all crossed out except the last one. The ink on the earlier ones had faded almost to nothing. She put it down and unconsciously wiped her hand on her tunic.

'What happens if a clown wants to use another clown's face?' she said.

'Oh, we compare all the new eggs with the ones on the shelves,' said Boffo. 'It's not allowed.'

They walked between aisles of faces. Angua fanded she could hear the squelch of a million custard-filled trousers and the echoes of a thousand honking noses and a million grins of faces that weren't smiling. About halfway along was a sort of alcove containing a desk and chair, a shelf piled with old ledgers, and a workbench covered with crusted pots of paint, scraps of coloured horsehair, sequins and other odds and ends of the egg-painter's spedalized art. Carrot picked up a wisp of coloured horsehair and twiddled it thoughtfully.

'But supposing,' he said, 'that a clown, I mean a clown with his own face . . . supposing he used another clown's face?'

'Pardon?' said Boffo.

'Supposing you used another clown's make-up?' said Angua.

'Oh, that happens all the time,' said Boffo. 'People're always borrowing slap off each other—'

'Slap?' said Angua.

'Make-up,' Carrot translated. 'No, I think what the lance-constable is asking, Boffo, is: could a clown make himself up to look like another clown?'

Boffo's brow wrinkled, like someone trying hard to understand an impossible question.

'Pardon?'

'Where's Beano's egg, Boffo?'

'That's here on the desk,' said Boffo. 'You can have a look if you like.'

An egg was handed up. It had a blobby red nose and a red wig. Angua saw Carrot hold it up to the light and produce a couple of red strands from his pocket.

'But,' she said, trying one more time to get Boffo to understand, 'couldn't you wake up one morning and put on make-up so that you looked like a different clown?'

He looked at her. It was hard to tell his expression under the permanently downcast mouth, but as far as she could tell she might as well have suggested that he performed a specific sex act with a small chicken.

'How could I do that?' he said. 'Then I wouldn't be me.'

'Someone else might do it, though?'

Boffo's buttonhole squirted.

'I don't have to listen to this sort of dirty talk, miss.'

'What you're saying, then,' said Carrot, 'is that no clown would ever make up his face in another clown's, um, design?'

'You're doing it again!'

'Yes, but perhaps sometimes by accident a young down might perhaps—'

'Look, we're decent people, all right?'

'Sorry,' said Carrot. 'I think I understand. Now . . . when we found poor Mr Beano, he didn't have his clown wig on, but something like that could easily have got knocked off in the river. But his nose, now . . . you told Sergeant Colon that someone had taken his nose. His real nose. Could you,' said Carrot, in the pleasant tones of someone talking to a simpleton, 'point to your real nose, Boffo?'

Boffo tapped the big red nose on his face.

'But that's—' Angua began.

'—your real nose,' said Carrot. 'Thank you.'

The clown wound down a little.

'I think you'd better go,' he said. 'I don't like this sort of thing. It upsets me.'

'Sorry,' said Carrot again. 'It's just that . . . I think I'm having an idea. I wondered about it before . . . and I'm pretty certain now. I think I know about the person who did it. But I had to see the eggs to be sure.'

'You saying another clown killed him?' said Boffo belligerently. ' 'Cos if you are, I'm going straight to—'

'Not exactly,' said Carrot. 'But I can show you the killer's face.'

He reached down and took something from the debris on the table. Then he turned to Boffo and opened his hand. He had his back to Angua, and she could not quite see what he was holding. But Boffo gave a strangled cry and ran away down the avenue of faces, his big shoes flip-flopping hugely on the stone flags.

'Thank you,' said Carrot, at his retreating back. 'You've been very helpful.'

He folded his hand again.

'Come on,' he said. 'We'd better begoing. I don't think we're going to be popular here in a minute or two.'

'What was that you showed him?' Angua asked, as they proceeded with dignity yet speed towards the gate.

'It was something you came here to find, wasn't it? All that stuff about wanting to see the museum—'

'I did want to see it. A good copper should always be open to new experiences,' said Carrot.

They made it to the gate. No vengeful pies floated out of the darkness.

Angua leaned against the wall outside. The air smelled sweeter here, which was an unusual thing to say about Ankh-Morpork air. But at least out here people could laugh without getting paid for it.

'You didn't show me what frightened him,' she said.

'I showed him a murderer,' said Carrot. 'I'm sorry. I didn't think he'd take it like that. I suppose they're all a bit wound up right now. And it's like dwarfs and tools. Everyone thinks in their own ways.'

'You found the murderer's face in there?'

'Yes.'

Carrot opened his hand.

It contained a bare egg.

'He looks like this,' he said.

'He didn't have a face?'

'No, you're thinking like a clown. I am very simple,' said Carrot, 'but I think what happened was this. Someone in the Assassins wanted a way of getting in and out without being seen. He realized there's only a thin wall between the two Guilds. He had a room. All he had to do was find out who lived on the other side. Later he killed Beano, and he took his wig and his nose. His real nose. That's how clowns think. Make-up wouldn't have been hard. You can get that anywhere. He walked into the Guild made up to look like Beano. He cut through the wall. Then he strolled down to the quad outside the museum, only this time he was dressed as an Assassin.

He got the . . . the gonne and came back here. He went through the wall again, dressed up as Beano, and strolled away. And then someone killed him.'

'Boffo said Beano looked worried,' said Angua.

And I thought: that's odd, because you'd have to see a clown right up close to know what his real expression was. But you might notice if the make-up wasn't on quite right. Like, maybe, if it was put on by someone who wasn't too used to it. But the important thing is that if another clown sees Beano's face go out of the door, he's seen the person leave. They can't think about someone else wearing that face. It's not how they think. A clown and his make-up are the same thing. Without his makeup a clown doesn't exist. A clown wouldn't wear another clown's face in the same way a dwarf wouldn't use another dwarfs tools.'

'Sounds risky, though,' said Angua.

'It was. It was very risky.'

'Carrot? What are you going to do now?'

'I think it might be a good idea to find out whose room was on the other side of the hole, don't you? I think it might belong to Beano's little friend.'

'In the Assassins' Guild? Just us?'

'Um. You've got a point.'

Carrot looked so crestfallen that Angua gave in.

'What time is it?' she said.

Carrot very carefully took Captain Vimes' presentation watch out of its cloth case.

'It's—'

—abing, abing, abong, bong . . . bing . . . bing . . .

They waited patiently until it had finished.

'A quarter to seven,' said Carrot. Absolutely accurate, too. I put it right by the big sundial in the University.'

Angua glanced at the sky.

'OK,' she said. 'I can find out, I think. Leave it to me.'

'How?'

'Er . . . I . . . well, I could get out of uniform, couldn't I, and, oh, talk my way in as a kitchen maid's sister or something . . .'

Carrot looked doubtful.

'You think that'll work?'

'Can you think of anything better?'

'Not right now.'

'Well, then. I'll . . . er . . . look . . . you go back to the rest of the men and . . . I'll find somewhere to change into something more suitable.'

She didn't have to look around to recognize where the snigger came from. Gaspode had a way of turning up silently like a small puff of methane in a crowded room, and with the latter's distressing ability to fill up all available space.

'Where can you get a change of clothes around here?' said Carrot.

A good Watchman is always ready to improvise,' said Angua.

'That little dog is awfully wheezy,' said Carrot. 'Why does he always follow us around?'