There were four levels underground. The first two both had just one door, set into the stone, but at last we came to the third, which had the three doors I'd seen the day before.

    'The middle one, as you know, is where Meg usually sleeps when I'm away' the Spook said.

    Now she'd been given a room upstairs, next to the Spook's, probably so that he could keep an eye on her - though based on the evidence from last night, she preferred to sleep in her rocking chair by the fire.

    'I don't use the others much' continued the Spook, 'but they can be very useful for keeping a witch locked up safely while all the arrangements are made-'

    'You mean while a pit is prepared?'

    'Aye, I do that, lad. As you'll have noticed, it's not like Chipenden here. I don't have the luxury of a garden so I have to make use of the cellar ...'

    The fourth and lowest level was, of course, the cellar itself. Even before we turned the final corner and it came into full view'I could hear things that made the candle tremble in my hand, sending the Spook's shadow dancing wildly.

    There were whisperings and groans and, worst of all, a faint sound of scratching. Being the seventh son of a seventh son I can hear things that most people can't but I never really get used to it. On some days I'm braver than others, that's all I can say. The Spook seemed calm enough but he'd been doing this for a lifetime.

    The cellar was big, even bigger than I'd expected, so big in fact that it must have been larger in area than the actual ground floor of the house. One wall was dripping with water and the low ceiling directly above it was oozing with damp, so I wondered if it was on the edge of the stream or actually underneath it.

    The dry part of the ceiling was covered in cobwebs, so thick and tangled that an army of spiders must have been at work. If just one or two had spun all that, I didn't want to meet them.

    I spent a lot of time looking at the ceiling and walls because I was delaying the moment when I had to look at the ground. But after a few seconds I could feel the Spook's eyes on me so I had no choice and finally forced myself to look down.

    I'd seen what the Spook kept in two of the gardens back at Chipenden. I suppose this was just more of the same, but whereas the graves and pits back there had been scattered among the trees where the sun occasionally shone to dapple the ground with shadows, here there were lots more and I felt trapped, closed in by the four walls and the low cobwebbed ceiling.

    There were nine witch graves in all, each one marked with a gravestone, and in front of this six feet of soil edged with smaller stones. Fastened to those stones by bolts, and covering each patch of earth, were thirteen thick iron bars. They'd been placed there to stop the dead witches under them clawing and scratching their way to the surface.

    Then, along one wall of the cellar, there were much heavier, larger stones. There were three of those and each one had been carved by the mason in exactly the same way:

    The Greek letter beta told anyone who could read the signs that boggarts were safely bound beneath them, and the Latin numeral T in the bottom right-hand corner said that they were of the first rank, deadly creatures capable of killing a man quicker than you could blink your eyes. Nothing new there, I thought, and as the Spook was good at his job there was nothing to fear from the boggarts who were trapped there.

    'There are two live witches down here as well,' said the Spook, 'and here's the first one,' he continued, pointing to a dark, square pit with a boundary of small stones crossed by thirteen iron bars to stop her from climbing out. 'Look at the corner stone,' he said, pointing downwards.

    I saw something then that I hadn't noticed before, even back in Chipenden. The Spook held his candle closer so that I could see it better. There was a sign, much smaller than that on the boggart stones, followed by the witch's name.

    'The sign is the Greek letter sigma because we classify all witches under 'S' for sorceress. There are so many types that, being female and subtle, they're often difficult to categorize precisely,' said the Spook. 'Even more so than a boggart, a witch has a personality that can change over time. So you have to refer to their history - the full history of each, bound or unbound, is recorded in the library back at Chipenden.'

    I knew that wasn't true of Meg. There was very little written about her in the Spook's library, but I didn't say anything. Suddenly I heard a faint stirring from the darkness of the pit and took a quick step backwards.

    'Is Bessy a first-rank witch?' I asked the Spook nervously, because they were the most dangerous and could kill. 'It isn't marked on the stone ...'

    'All the witches and boggarts in this cellar are first rank,' the Spook told me, 'and I bound 'em all so if s not always worth putting the mason to extra trouble with the carving, but there's nothing to fear here, lad. Old Bessy's been in there a long time. We've disturbed her and she's just turning over in her sleep, that's all. Now come over here and look at this . . .'

    It was another witch pit, exactly like the first one, but I suddenly shivered with cold. Something told me that whatever was in that pit was much more dangerous than Bessy, who was asleep and just trying to get herself comfortable on the cold, damp ground.

    'You might as well take a closer look, lad,' said the Spook, 'so that you can see what we're dealing with. Hold up your candle and look down but be sure to keep your feet well back!'

    I didn't want to do it but the Spook's voice was firm. It was a command. To look down into the pit was part of my training, so I had no choice.

    I leaned my body forwards, keeping my toes well back from the bars, and held the candle up so that it cast a flickering yellow light down into the pit. At that very moment I heard a noise from below and something big scuttled across the floor and into the dark shadows in the near corner. It sounded wick with life, as if it could scamper up the wall of the pit faster than you could blink!

    'Hold your candle right over the bars and take a proper look!' commanded the Spook.

    I obeyed, holding it out at arm's length. At first all I could see were two large cruel eyes staring up at me, two points of fire reflecting the candle flame. As I looked more carefully, I saw a large gaunt face framed by a tangle of thick greasy hair, and a squat scaly body below it. There were four limbs and they were more like arms than legs, with large elongated hands that ended in long sharp claws.

    I shuddered and my hand trembled so much that I almost dropped the candle through the bars. I stepped back too quickly and nearly fell over, but the

    Spook caught hold of my shoulder and steadied me.

    'Not a pretty sight, is it, lad' he muttered, shaking his head. 'What we've got down there is a lamia witch. She looked human enough over twenty years ago when I first put her there. Now she's become feral again. That's what happens when you put a lamia witch in a pit. Deprived of human companionship, she slowly reverts to type. And even after all these years she's still strong. That's why I have the iron gate on the stairs. If she ever managed to get out of here, that would slow her up for a while.

    'And that's not all, lad. You see, a normal witch pit isn't good enough for her. There are iron bars on the sides and bottom of the pit too, buried under the soil. So she's really in a cage. That and a layer of salt and iron beyond that. She can dig fast and deep with those four clawed hands as well, so it's the only way we can stop her getting out! Anyway, do you know who she is?'