Later, when I woke up, I couldn’t remember what it was – dreams are like that sometimes – but I knew it had been sent by a witch seeking revenge for something I’d done to her.

In my dream, a church bell began to chime somewhere in the distance. I froze, petrified, but on the twelfth note I began to run towards it. Branches whipped at my face as I sprinted desperately through the trees. Something was chasing me now, but it wasn’t footsteps that I heard: it was the beating of wings.

I glanced back over my shoulder and saw that my pursuer was a large black crow. The sight of it filled me with terror, but I knew that if only I could reach the church I’d be safe. Why that should be I don’t know – churches aren’t usually places of refuge from the dark. Spooks and apprentices relied on the tools of their trade and the knowledge they’d gained. Nevertheless, in that nightmare I knew that I had to reach the church or die.

I suddenly tripped over a root and sprawled headlong. Winded, I struggled to my knees and looked up at the crow, which had alighted on a branch. The air shimmered in front of me and I blinked furiously to clear my vision. When I could finally see again, I was confronted by a figure in a long black dress. She was female from the neck down but had the huge head of a crow.

Even as I stared, the crow’s head began to change. The beak shrank, and the eyes shifted shape until the head was fully human. And I knew that face. It was that of a witch who was now dead.

I must have cried out on awaking from that dream. The Spook was still fast asleep, but as I sat up, shuddering, Alice’s arm went around my shoulders.

‘You all right, Tom?’ she whispered.

I nodded. ‘Just a nightmare – that’s all.’

‘Want to tell me about it?’

I gave Alice a short account of what I’d dreamed. ‘I think the crow was the Morrigan, the dark goddess worshipped by Celtic witches,’ I added. ‘No doubt it harks back to the time when Bill Arkwright and I faced a Celtic witch who’d travelled to the County. She summoned the Morrigan, who attacked me in the shape of a crow, but I somehow managed to drive it off. The witch warned me then never to visit Ireland. She said the Morrigan was much more powerful there and would seek her revenge on me.’

‘Well, that explains your nightmare, Tom. Don’t worry, we’re not in Ireland. We’ll be heading back to the County once we’ve dealt with Lizzie.’

I knew that Alice was just trying to comfort me, but I felt gloomy about the future. ‘There’s little chance of that while it’s still in enemy hands,’ I observed.

‘As Old Gregory once said, wars don’t last for ever,’ Alice remarked cheerfully. ‘Anyway, what happened to that Celtic witch?’

‘Bill Arkwright killed her with his knife. Right at the end of my nightmare, the crow took on her dead face. That was the scariest thing of all.’ The Spook had become very quiet and withdrawn, giving me just an hour of instruction a day, studying the Old Tongue. Then, using the large notebook that he always carried in his bag, he spent the rest of the time writing. I noticed that he was making sketches as well.

‘What are you doing?’ I asked, curiosity getting the better of me.

‘I’ve got to start somewhere, lad,’ he told me in one of his rare talkative moments. ‘All that’s left of my library is the Bestiary, so I’m going to try and rewrite some of the other books that were lost. I’ve got to do it before I forget. I’m starting with A History of the Dark. The lessons we learn from history are important – they keep us from repeating past mistakes.’

I felt that we should be using this time to work out how to deal with Lizzie. Most days we discussed it briefly, but the Spook seemed lost in thought and contributed little to our discussions. Yes, the books did need to be rewritten, but it seemed to me that he was distracting himself from the real problem – a witch who was growing more and more powerful. Exactly seven days after our arrival at the cottage, we had a visitor: Alice opened the kitchen door to throw out some food scraps and a bird flew straight into the room – a grey pigeon. But instead of flapping about in panic, it landed on the table.

‘Bad luck for a bird to fly into a room!’ Alice said. ‘It means someone’s going to die soon.’

‘Well, you’re not always right, girl. Besides, I think this one has a message for us,’ said the Spook, pointing to a piece of paper tied to the pigeon’s leg.

He held out his hand and the bird hopped onto it. Carefully he took it in his hands and held the creature out towards me. ‘Untie the message, lad. Be as gentle as you can…’

I did as he asked. The piece of paper was tied on so that it wouldn’t come loose, yet one gentle pull on the end of the string, and the pellet of paper dropped into my hand. While the Spook gave the bird some crusts of bread and water, I unfolded the small square of paper and smoothed it out on the table. The writing was very small and difficult to make out.

‘It’s from Adriana,’ I said. ‘She says it’s safe to return, but there’s bad news as well.’

‘Well, read it out, lad!’

So I did as my master commanded. ‘Dear Mr Gregory, Tom and Alice,

Soon after you left, the yeomanry searched the area, but I stayed hidden close to the house and they passed me by.

The witch is still at Greeba Keep: I hear strange tales of what is happening there, and I have much to tell you, so please hasten back immediately.

I have bad news too: five days ago my mother died. So the witch killed both my parents. I owe her for that and intend to repay her fully. Yours sincerely, Adriana.’

‘Poor girl,’ said the Spook. ‘Well, let’s get back to the mill and see what the latest news is. I fear the worst.’

Within the hour we were on our way back to Peel.

We arrived just in time for the evening meal. Adriana had sent the cook home early and prepared a lamb stew herself. Simon helped serve us. It was the best food I’d eaten in weeks, and she’d provided each of us with a large cup of mead, a delicious drink made from honey, the sweetness tempered with aromatic spices.

When the Spook had offered his condolences for the death of her mother, Adriana had wept bitterly.

‘Well,’ said my master now, sipping from his cup of mead. ‘I’ve tried to be patient but I can’t wait any longer. What are the strange tales from Greeba Keep that you mentioned in your letter?’

‘Terrifying things have been seen in the surrounding woods – all manner of monsters and daemons-’

‘The buggane can take on many different shapes,’ interrupted the Spook.

‘These things weren’t seen in the buggane’s domain,’ Adriana replied, ‘but much further to the north. Sheep and cattle have gone missing too. All that remained was small fragments of bone.’

The Spook pulled at his beard. ‘What about the sightings? Were the witnesses reliable?’ he asked.

Adriana shrugged. ‘Some are more reliable than others, but one was a forester, a dour, plain-speaking man not given to flights of fancy. He also saw strange dancing lights – he counted seven. When they approached him, he fled. Could they be the same lights we saw in the cavern?’

‘He did well to run,’ said the Spook. ‘That coven of witch spirits could have drained his life force in minutes. This is all very bad news. It means that denizens of the dark visiting the cache of animas can now use its power to wander far beyond it. They’re a threat to your whole island and possibly beyond.’

‘Can anything be done?’ asked Adriana.

‘Aye – killing the buggane would stop it. The cache is only attractive while it continues to grow. Without an active buggane, such power soon starts to diminish. What else?’ asked the Spook. ‘Is there any more news of the bone witch?’

‘She took her force of yeomen back to Greeba, but then paid them off and dismissed the majority within a few days, retaining only about fifty for guard duty.’