'Oh, there was a lot of us kids at home and it was rainin' a lot and you need a lot of privacy for really good geology,' said Nanny vaguely. 'I think his hammer's still around here somewhere. He quite forgot about it after a while. Mind how you tread, the rocks is very slippery. How's young Esme doing, Magrat?'

'Oh, gurgling away. I'll have to feed her soon.'

'We've got to look after her,' said Nanny.

'Well, yes. Of course.'

Nanny clapped her hands together and pulled them apart gently. The glow between them wasn't the showy light that wizards made, but a grainy graveyard glimmer. It was just enough to ensure that no one fell down a hole.

'Probably some dwarfs in a place like this,' said Magrat, as they picked their way along a tunnel.

'Shouldn't think so. They don't like places that don't stay the same. No one comes up here now but animals and Granny when she wants to be alone with her thoughts.'

'And you when you were banging rocks,' said Magrat.

'Hah! But it was different then. There was flowers on the moor and the bridge was just stepping stones. That's 'cos I was in love.'

'You mean it really does change because of the way you feel?' said Agnes.

'You spotted it. It's amazing how high and rocky the bridge can be if you're in a bad mood, I know that.'

'I wonder how high it was for Granny, then?'

'Probably clouds could go underneath, girl.'

Nanny stopped where the path forked, and then pointed.

'I reckon she's gone this way. Hold on-'

She thrust out an arm. Stone groaned, and a slab of roof thudded down, throwing up spray and pebbles.

'So we'll just have to climb over this bit, then,' Nanny went on, in the same matter-of-fact tone of voice.

'Something's trying to push us out,' said Agnes.

'But it won't,' said Nanny. 'And I don't think it'll harm us.'

'That was a big slab!' said Agnes.

'Yeah. But it missed us, didn't it?'

There was an underground river further on, sheer white water blurred with speed. It poured around and almost over a dam of driftwood, topped by an inviting long log.

'Look, this isn't safe for the baby!' said Agnes. 'Do you both see that? You're her mother, Magrat!'

'Yes, I know, I was there,' said Magrat, with infuriating calm. 'But this doesn't feel,unsafe. Granny's here somewhere.'

'That's right,' said Nanny. 'Really close now, I think.'

'Yes, but she can't control rivers and rocks-' Agnes began.

'Here? Dunno. Very... responsive place, this.'

They inched their way across the log, passing the baby from one to the other.

Agnes leaned against the stone wall. 'How much further?'

'Well, technic'ly a few inches,' said Nanny. 'That's helpful to know, isn't it?'

'Is it just me,' said Magrat, 'or is it getting warmer?'

'Now that,' said Agnes, pointing ahead, 'I don't believe.'

At the end of a slope a crevasse had opened in the rock. Red light spilled out. As they stared at it, a ball of flame rolled up and burst across the ceiling.

'Oh deary deary me,' said Nanny, who had taken a turn to carry the baby. 'An' it's not even as if there's any volcanoes anywhere near here. What can she be thinking?' She headed purposefully towards the fire.

'Careful!' Agnes shouted. 'Perdita says it's real!'

'What's that got to do with the price of fish?' said Nanny, and stepped into the fire.

The flames snapped out.

The other two stood in the chilly, damp gloom.

Magrat shuddered. 'Nanny, you are carrying the baby.'

'The harm you come to here is what you brings with you,' said Nanny. 'And it's Granny's thoughts that are shaping this place. But she wouldn't raise a hand to a child. Couldn't do it. Hasn't got it in her.'

'This place is reacting to what she's thinking?' said Agnes.

'I reckon so,' said Nanny, setting off again.

'I'd hate to be inside her head!'

'You nearly are,' said Nanny. 'Come on. We've passed the fire. I don't think there'll be anything else.'

They found her in a cavern. It had sand on the floor, smooth and unmarked by anything except one set of footprints. Her hat had been placed neatly beside her. Her head rested on a rolled-up sack. She held a card in stiff hands.

It read:

GOE AWAY

'That's not very helpful,' said Magrat, and sat down with the baby across her lap. 'After all this, too.'

'Can't We wake her up?' said Agnes.

'That's dangerous,' said Nanny Ogg. 'Trying to call her back when she ain't ready to come? Tricky.'

'Well, can we at least take her out of here?'

'She won't bend round corners but, hah, maybe we could use her as a bridge,' said Nanny. 'No, she came here for a reason...'

She pulled the sack out from under Granny's head, which did not move, and opened it.

'Wrinkly apple, bottle of water and a cheese sandwich you could bend horseshoes round,' she said. 'And her old box.'

She set it down on the floor between them.

'What is in there?' said Agnes.

'Oh, keepsakes. Memorororabiliha, like I said. That sort of thing,' said Nanny. 'She always says it's full of things she's got no further use for.' She drummed her fingers on the box as if accompanying a thought on the piano, and then picked it up.

'Should you do that?' said Agnes.

'No,' said Nanny. She lifted out a bundle of papers tied with ribbon and put them on one side.

They all saw the light shining up from underneath. Nanny reached in and took out a small glass medicine bottle, tightly corked, and held it up. A little glow inside was quite bright in the gloom of the cave.

'Seen this bottle before,' said Nanny. 'She's got all kinds of odds and ends in here. Never noticed it glowing, though.'

Agnes took the bottle. Inside there was what looked like a piece of fern, or... no, it was a feather, quite black except for the very tip, which was as yellow and bright as a candle flame.

'Do you know what it is?'

'No. She's always pickin' up stuff. She's had the bottle a long time, 'cos I've seen it in there-'

'I faw her fick it uff-' Magrat removed a safetypin from her mouth. 'I saw her pick that thing up years ago,' she tried again. 'It was around this time of year, too. We were walking back through the woods and there was a shooting star and this sort of light fell off it and we went to look and there it was. It looked like a flame but she was able to pick it up.'

'Sounds like a firebird feather,' said Nanny. 'There used to be old stories about them. They pass through here. But if you touch their feathers you'd better be damn sure of yourself, because the old stories say they burn in the presence of evil-'

'Firebird? You mean a phoenix?' said Agnes. 'Hodgesaargh was going on about one.'

'Haven't seen one go over for years,' said Nanny. 'Sometimes you'd see two or three at a time when I was a girl, just lights flying high up in the sky.'

'No, no, the phoenix... there's only one of it, that's the whole point,' said Agnes.

'One of anything's no bloody use,' said Nanny.

Granny Weatherwax smacked her lips, like someone emerging from a very deep sleep. Her eyelids flickered.

'Ah, I knew opening her box'd work,' said Nanny happily.

Granny Weatherwax's eyes opened. She stared straight up for a moment, and then swivelled them towards Nanny Ogg.

'W't'r,' she mumbled. Agnes hastily passed her the water bottle. She touched Granny's fingers, and they were as chilly as stone.

The old witch took a gulp.

'Oh. It's you three,' she whispered. 'Why did you come here?'

'You told us to,' said Agnes.

'No, I didn't!' Granny snapped. 'Wrote you a note, did I?'

'No, but the stuff-' Agnes stopped. 'Well, we thought you wanted us to.'

'Three witches?' said Granny. 'Well, no reason why not. The maiden, the mother and the-'

'Go carefully,' Nanny Ogg warned.