Belmont wasn't very large - just a crossroads with half a dozen houses and the smithy we'd come to visit. The blacksmith didn't seem very pleased to see us, but that was probably because our knocking got him out of bed. He was big and muscular like most smiths, certainly not a man to trifle with, but he looked at the Spook warily and seemed ill at ease. He knew my master's trade all right.

    'I need a new axe,' said the Spook.

    The smith pointed to the wall behind the forge, where a number of axe-heads were displayed, roughly shaped ready for their final finish.

    The Spook chose quickly, pointing to the biggest. It was a huge double blade and the blacksmith looked my master up and down quickly, as if judging whether he was big and strong enough to wield it.

    Then, without further ado, he nodded, grunted and set to work. I stayed by the forge, watching while the blacksmith heated, beat and shaped that axe-head on his anvil, every so often quenching it in a tub of water with a great sizzle and cloud of steam.

    He hammered it onto a long wooden shaft before sharpening it at the grindstone, the sparks flying. In all, it was almost an hour before the blacksmith was finally satisfied and passed the axe to my master.

    'Next I need a large shield,' said the Spook. 'It has to be big enough to protect the two of us yet light enough for the lad to hold at arm's length above his head.'

    The blacksmith looked surprised but went into his store at the back and returned with a large circular shield. It was made of wood with a metal rim. It also had an iron centre-boss with a spike, so the blacksmith began by removing this and replacing it with more wood to make the shield lighter. Then he covered the outside of the shield with tin.

    By gripping its outer edge, I was now able to hold the shield above my head with both arms outstretched. The Spook said that wouldn't do because my fingers could get hurt and I might drop the shield. So the usual leather strap was replaced by two wooden handles just inside the rim.

    'Right, let's see what you can do,' said the Spook.

    He made me hold the shield in different positions at different angles and then, satisfied at last, he paid the blacksmith and we set off back towards Stone Farm.

    We went up onto the fell right away. The Spook had to leave his staff behind because he had his hands full carrying the axe and his own bag. I was struggling with the heavy shield, glad that he didn't expect me to carry his bag as well. We climbed until we reached the place where the man had died. Then the Spook paused and looked hard into my eyes.

    'You need to be brave now, lad. Very brave. And we have to work quickly,' he told me. 'The boggart's living under the roots of an old thorn tree up yonder. We have to cut down and burn the tree to drive it out.'

    'How do you know that?' I asked. 'Do stone-chuckers usually live under tree roots?'

    'They live anywhere that takes their fancy. But generally boggarts do like living in cloughs, and particularly under the roots of thorn trees. The shepherd was killed at the foot of this clough right here. And I know there's a thorn tree further up because that's exactly where I dealt with the last one, almost nineteen years ago, when young John was just a babe in arms and Morgan was my apprentice. But that's given us a problem because whereas that boggart listened to a bit of friendly persuasion and moved on when I asked, this is a rogue stone-chucker that's already killed so words won't be enough.'

    So then, heading due north, we entered the western edge of the clough, the Spook setting a fast pace ahead of me: soon we were both breathing hard. The mud gradually gave way to loose stones, making it difficult underfoot.

    At first we kept close to the top of the clough, but then the Spook led the way down the scree until we reached the edge of the stream. It was shallow and narrow but still it boiled across the stones, rushing downwards with such force that it would have been difficult to cross. We continued upwards against its flow, the banks on either side rising up steeply until only a narrow crack of sky was visible overhead. Then, despite the noise of the stream, I heard the first pebble drop into the water just ahead.

    It was something I'd been expecting, and soon there were others, forcing me to take the shield from my back and try to hold it over our heads. The Spook was taller than me so I had to hold it up high, and it wasn't long before my shoulders and arms began to ache. Even though I held it at arm's length, the Spook was forced to stoop and progress wasn't comfortable for either of us.

    Soon we came in sight of the thorn tree. It wasn't particularly big but it was an ancient tree, black and twisted, with gnarled roots that resembled claws. It stood defiant, having survived the worst of the weather for a hundred years or more. It was a good place for a boggart to make its home, especially a stone-chucker like this, a type that avoided human company and liked to be alone.

    The falling stones were getting larger by the minute, and just as we reached the tree, one bigger than my fist clanged onto the shield, nearly deafening me.

    'Hold it steady lad!' the Spook shouted.

    Then the stones stopped falling.

    'Over there . . .' My master pointed, and in the darkness below the tree's branches I could see the boggart starting to take shape. The Spook had told me that this type of boggart was really a spirit and had no flesh, blood and bone of its own; but sometimes, when it tried to scare people, it covered itself with things that made it visible to human eyes. This time it was using the stones and mud from beneath the tree. They rose up in a big whirling wet cloud and stuck to it so that its shape could be seen.

    It wasn't a pretty sight. It had six huge arms which, I suppose, were pretty useful for throwing stones. No wonder it could hurl so many so fast. Its head was enormous too, and its face covered with mud, slime and pebbles that moved when it scowled at us, just as if an earthquake were taking place underneath. There was a black slit for a mouth and two large black holes where its eyes should have been.

    Ignoring the boggart and wasting no time, as stones started to shower down again, the Spook went straight for the tree, the axe already swinging down as he reached it. The gnarled old wood was tough and it took quite a few blows to lop off its branches. I'd lost sight of the boggart, being too busy trying to hold the shield up and ward off the worst of the stones that came our way. The shield seemed to be getting heavier by the minute and my arms were trembling with the effort of holding it aloft.

    The Spook attacked the trunk, striking at it in a fury. I knew then why he'd chosen an axe with a double-blade: he swung it both forehand and backhand in huge scything arcs, so that I felt in danger of my life. Looking at him, you'd never have guessed he was so strong. He was a long way from being young, but I knew then, by the way the axe-blade bit deep into the wood, that despite his age and recent ill health he was still at least as strong as the blacksmith and would have made two of my dad.

    The Spook didn't chop the tree right down; he split the trunk, then put down the axe and reached into his black leather bag. I couldn't see what he was doing properly because the stones began to rain down harder than ever. I glanced sideways and saw the boggart begin to ripple and expand: huge bulging muscles were erupting all over its body like angry boils. And, as more mud and pebbles flew up, it almost doubled in size. Then two things happened in quick succession.

    The first was that a huge boulder fell out of the sky to our right and buried itself half in the ground. If that had landed on top of us, the shield would have been useless. We'd both have been flattened. The second was that the tree suddenly burst into flames. As I said, I didn't get a chance to see how the Spook managed it, but the result was certainly spectacular. The tree went up with a great whoosh and flames lit up the sky, sparks crackling away in every direction.