Granny walked over and tapped her on the shoulder. ‘They’ve gone, Gytha.’

‘Rhuba- Oh, hello, Esme,’ said Nanny, lowering the implements of righteous retribution. ‘I was just tagging along to see it didn’t get out of hand. Was that Greebo I saw just then?’

‘Yes.’

‘Awww, bless him,’ said Nanny. ‘He looked a bit bothered, though. I hope he doesn’t happen to anybody.’

‘Where’s your broomstick?’ said Granny. ‘It’s in the cleaners’ cupboard backstage.’

‘Then I’ll borrow it and keep an eye on things,’ said Granny. ‘Hey, he’s my cat, I ought to be looking after him-‘ Nanny began. Granny stepped aside, revealing a huddled shape sitting hugging its knees. ‘You look after Walter Plinge,’ she said. ‘It’s something you’d be better at than me.’

‘Hello Mrs Ogg!’ said Walter, mournfully. Nanny looked at him for a moment. ‘So he is the-?’

‘Yes.’

‘You mean he really did do the mur-?’

‘What do you think?’ said Granny. ‘Well, if it comes to it, I think he didn’t,’ said Nanny. ‘Can I have a word in your ear, Esme? I don’t reckon I should say this in front of young Walter.’ The witches bent their heads together. There was a brief whispered conversation. ‘Everything is simple when you know the answer,’ said Granny. ‘I’ll be back soon.’ She hurried off. Nanny heard her shoes clattering on the stairs. Nanny looked down at Walter again, and held out her hand. ‘Up you get, Walter.’

‘Yes Mrs Ogg!’

‘I expect we’d better find somewhere for you to lie low, eh?’

‘I know a hidden place Mrs Ogg!’

‘You do, do you?’ Walter lurched across the roof towards another trapdoor, and pointed to it proudly. ‘That?’ said Nanny. ‘That doesn’t look very hidden to-me, Walter.’ Walter gave it a puzzled look, and then grinned in the way a scientist might after he’d solved a particularly difficult equation. ‘It’s hidden where everyone can see it Mrs Ogg!’ Nanny gave him a sharp look, but there was nothing but a slightly glazed innocence in Walter’s eyes. He lifted up the trapdoor and pointed politely downwards. ‘You go down the ladder first so I will not see your drawers!’

‘Very. . . kind of you,’ said Nanny. It was the first time anyone had ever said anything like that to her. The man waited patiently until she had reached the bottom of the ladder, and then climbed laboriously down after her. ‘This is just an old staircase, isn’t it?’ said Nanny, prodding at the darkness with her torch. ‘Yes! It goes all the way down! Except at the bottom where it goes all the way up!’

‘Anyone else know about it?’

‘The Ghost Mrs Ogg!’ said Walter, climbing down. ‘Oh, yes,’ said Nanny slowly. ‘And where’s the Ghost now, Walter?’

‘He ran away!’ She held up the torch. There was still nothing to be read in Walter’s expression. ‘What does the Ghost do here, Walter?’

‘He watches over the Opera!’

‘That’s very kind of him, I’m sure.’ Nanny started downwards, and as the shadows danced around her she heard Walter say: ‘You know she asked me a very silly question Mrs Ogg! It was a silly question any fool knows the answer!’

‘Oh, yes,’ said Nanny, peering at the walls. ‘About houses on fire, I expect. . .’

‘Yes! What would I take out of our house if it was on fire!’

‘I expect you were a good boy and said you’d take your mum,’ said Nanny. ‘No! My mum would take herself!’ Nanny ran her hands over the nearest wall. Doors had been nailed shut when the staircase had been abandoned. Someone walking up and down here, with a keen pair of ears, could hear a lot of things. . . ‘What would you take out then, Walter?’ she said. ‘The fire!’ Nanny stared unseeing at the wall, and then her face slowly broke into a grin. ‘You’re daft, Walter Plinge,’ she said. ‘Daft as a broom Mrs Ogg!’ said Walter cheerfully. But you ain’t insane, she thought. You’re daft but you’re sane. That’s what Esme would say. And there’s worser things. Greebo pounded along Broadway. He was suddenly not feeling very well. Muscles were twitching in odd ways. A tingling at the base of his spine indicated that his tail wanted to grow, and his ears definitely wanted to creep up the sides of his head, which is always embarrassing when it happens in company. In this case the company was about a hundred yards behind and apparently intent on moving his ears quite a long way from their current position, embarrassment or not. It was gaining, too. Greebo normally had a famous turn of speed, but not when his knees were trying to reverse direction every few seconds. His normal plan when pursued was to jump on to the water-butt behind Nanny Ogg’s cottage and rake the pursuer across the nose with his claws when it came around the corner. Since this would now involve a fivehundred-mile dash, an alternative had to be sought. There was a coach waiting outside one of the houses. He lurched over to it, pulled himself up, grabbed the reins and briefly turned his attention to the driver. ‘Get orffl.’ Greebo’s teeth shone in the moonlight. The coachman, with great presence of mind and urgent absence of body, somersaulted backwards into the night. The horses reared, and tried to break into a gallop from a standing start. Animals are less capable of being fooled than are humans; they knew that what they had behind them was a very large cat, and the fact that it was manshaped didn’t make them any happier. The coach lumbered off. Greebo looked over his twitching shoulder at the torch lit crowd and waved a paw derisively. The effect pleased him so much that he clambered on to the roof of the swaying coach and continued to jeer. It is a cat-like attribute to spit defiance at the enemy from a place of safety. In the circumstances it would have been better if cat-like attributes had included the ability to steer. A wheel hit the parapet of the Brass Bridge and scraped along it, the iron rim kicking up sparks. The shock knocked Greebo from his perch in mid-gesture. He landed on his feet in the middle of the road, while the

terrified horses continued on with the coach rocking dangerously from side to side. The pursuers stopped. ‘What’s he doing now?’

‘He’s just standing there.’

‘There’s only one of him and there’s lots of us, right? We could easily overpower him.’

‘Good idea. On the count of three, we’ll all rush him, right? One. . . two. . . three. . .’Pause. ‘You didn’t run.’

‘Well, nor did you.’

‘Yes, but I was the one saying “one, two, three”.’

‘Remember what he did to Mr Pounder!’

‘Yes, well, I never liked the man all that much. . .’ Greebo snarled. Ticklish things were happening to his body. He threw his head back and roared. ‘Look, at worst he’d only be able to get one or two of us’

‘Oh, that’s good, is it?’

‘Here, why’s he twisting around like that?’

‘Maybe he hurt himself falling off the coach-‘

‘Let’s get .him!’ The mob closed in. Greebo, struggling against a morphogenic field swinging wildly between species, punched the first man in the face with a hand and clawed the shirt off another man with something more like a giant paw. ‘Oh, shiiiooooo-‘ Twenty hands grabbed him. And then, in the melee and the darkness, twenty hands were holding just cloth and emptiness. Vengeful boots connected with nothing more than air. Clubs that had been swung at a snarling face whirled through empty space and returned to hit their owner on the ear. ‘-ooooaaawwwwl!’ Quite unnoticed in the scrum, a flat-eared bullet of grey fur shot out from between the scuffling legs. The kicking and punching stopped only when it became apparent that all the mob was attacking was itself. And, since the IQ of a mob is the IQ of its most stupid member divided by the number of mobsters, it was never very clear to anyone what had happened. Obviously they’d closed in on the Ghost, and he certainly couldn’t have escaped. All that was left was a mask and some torn clothing. So, the mob reasoned, he must have ended up in the river. And good riddance, too. Happy in the knowledge of a job well done, they adjourned to the nearest pub. This left Sergeant Count de Tritus and Corporal the Count de Nobby Nobbs, who lurched to the middle of the bridge and regarded the few scraps of cloth. ‘Commander Vimes isn’t. . .isn’t. . . isn’t goin’ to like dis,’ said Detritus. ‘You know he likes prisoners to be alive.’

‘Yeah, but this one would’ve been hung anyway,’ said Nobby, who was trying to stand upright. ‘This way was just a bit more. . . democratic. A great saving in terms of rope, not to mention wear and tear on locks and keys.’ Detritus scratched his head. ‘Shouldn’t there be some blood?’ he ventured. Nobby gave him a sour look. ‘He couldn’t’ve got away,’ he said. ‘So don’t go asking questions like that.’

‘Only, if humans is hit hard enough, they leaks all over der place,’ said Detritus. Nobby sighed. That was the calibre of people you got in the Watch these days. They had to make a mystery of things. In days gone by, when it had

been just the old gang and an unofficial policy of lazy fair, they’d have said a heartfelt ‘Well done, lads’ to the vigilantes and turned in early. But now old Vimes had been promoted to Commander he seemed to be enrolling people who asked questions all the time. It was even affecting Detritus, considered by other trolls to be as dim as a dead glowworm. Detritus reached down and picked up an eye patch. ‘What d’you think, then?’ said Nobby scornfully. ‘You think he turned into a bat and flew away?’

‘Ha! I do not t’ink that ‘cos it is in. . . consist. . . ent with modern policing,’ said Detritus. ‘Well, I think,’ said Nobby, ‘that when you have ruled out the impossible, what is left, however improbable, ain’t worth hanging around on a cold night wonderin’ about when you could be getting on the outside of a big drink. Come on. I want to try a leg of the elephant that bit me.’

‘Was dat irony?’

‘That was metaphor.’ Detritus, uneasy in what was technically his mind, prodded at the torn pieces of clothing. Something brushed against his leg. It was a cat. It had tattered ears, one good eye, and a face like a fist with fur on it. ‘Hello, little cat,’ said Detritus. The cat stretched and grinned. ‘Gerrt lorssst, coppuurrrr. . .’ Detritus blinked. There are no such things as troll cats, and Detritus had never seen a cat before he’d arrived in AnkhMorpork and discovered that they were very, very hard to eat. And he’d never heard of them talking. On the other hand, he was very much aware of his reputation as the most stupid person in the city, and he wasn’t going to draw attention to a talking cat if it were going to turn out that everybody except him knew that they talked all the time. In the gutter, a few feet away, there was something white. He picked it up carefully. It looked like the mask the Ghost had worn. This was probably a Clue. He waved it urgently. ‘Hey, Nobby-‘

‘Thank you.’ Something dipped through the darkness, snatched the mask from the troll’s hand, and soared into the night. Corporal Nobbs turned around. ‘Yes?’ he said. ‘Er. . . how big are birds? Normally?’

‘Oh, blimey, I dunno. Some are small, some are big. Who cares?’ Detritus sucked his finger. ‘Oh, no reason,’ he said. ‘I am far too smart to be taken in by perfec’ly normal t’ings.’ Something squelched underfoot. ‘It’s pretty damp down here, Walter,’ said Nanny. And the air was stale and heavy and seemed to be squeezing the light from the torch. There was a dark edge to the flame. ‘Not far now Mrs Ogg!’ Keys jingled in the darkness, and some hinges creaked. ‘I found this Mrs Ogg! It’s the Ghost’s secret cave!’

‘Secret cave, eh?’

‘You got to shut your eyes! You got to shut your eyes!’ said Walter urgently. Nanny did so, but to her shame kept a grip on the torch, just in case. She said: ‘And is the Ghost in there, Walter?’

‘No!’ There was the rattle of a matchbox and some scuffling, and then ‘You can open them now Mrs Ogg!’ Nanny did so.

Colour and light blurred and then swam into focus, first in her eyes and then, eventually, in her brain. ‘Oh, my,’ she murmured. ‘Oh, my, my. . .’ There were candles, the big flat ones used to illuminate the stage, floating in shallow bowls. The light they gave was soft, and it rippled over the room like the soul of water. It glinted off the beak of a huge swan. It glittered in the eye of a vast, sagging dragon. Nanny Ogg turned slowly. Her experience of opera had not been a lengthy one but witches pick things up quickly, and there was the winged helmet worn by Hildabrun in The Ring of the Nibelungingung, and here was the striped pole from The Barber of Pseudopolis, and there was the pantomime horse with the humorous trapdoor from The Enchanted Piccolo, and here. . . . . .here was opera, all piled in a heap. Once the eye had taken it all in, it had time to notice the peeling paint and rotting plaster and the general air of gentle mouldering. The decrepit props and threadbare costumes had been dumped in here because people didn’t want them anywhere else. But someone did want them here. After the eye had seen the ruin, then there was time for it to see the little patches of recent repair, the careful areas of fresh paint. There was something like a desk in the tiny area of floor not occupied by the props. And then Nanny realized that it had a keyboard and a stool, and there were neat piles of paper on top of it. Walter was watching her with a big, proud grin. Nanny ambled over to the thing. ‘It’s a harmonium, ain’t it? A tiny organ?’