The union between the Fiend and a witch could produce a wide range of different offspring. Grimalkin, the witch assassin, had once given birth to a perfectly human baby boy; the Fiend had killed it on the spot for just that reason. Then there was Alice, born fully human but with the potential to become a powerful witch. Here, at the other end of the scale, was this daemonic figure, a horned beast like the father who’d sired him.

The Spook readied his staff and approached the creature.

The abhuman hissed at him through his teeth, then spoke in a harsh voice. ‘Follow me,’ he rasped.

‘And why should we do that?’ demanded my master, raising his staff threateningly.

‘Follow me,’ Horn repeated. He turned and headed into the darkness.

I didn’t like the idea of leaving the relative safety of the rock wall. I had a bad feeling about venturing out into the vastness of the cavern: you could get lost; or just be swallowed up by the darkness.

‘Wait!’ cried the Spook, no doubt thinking the same thing. ‘You need to give us a good reason to follow you – otherwise we stay here!’

The abhuman turned back to face us, and his face twisted in anger, the glare of a feral beast rather than a human being. ‘You must follow. You have no choice.’

‘There’s always a choice to be made,’ said the Spook. ‘Aye, there’s always that. Suppose we choose to stay here…’

‘Then you will stay here in this cavern until you die. There is no escape from here unless I wish it. Now that my master is dead, I control the buggane. Despite all the efforts of the witch, it still does as I command – at least for the moment.’

‘He could be lying,’ Adriana said, lowering her voice. ‘It’s safer to stay here.’

‘Not if all the entrances and exits are made by the buggane,’ I replied.

‘And I suspect that’s exactly what we’ll find,’ said the Spook. ‘I fear that the wisest option for now is to do as he asks.’

So we reluctantly followed the abhuman into the cavern. Soon the walls were far behind us and we continued in the pool of yellow light cast by our lanterns, beyond which nothing seemed to exist. Darkness extended in every direction. Our footsteps echoed in the silence and I grew increasingly nervous.

The situation soon became even worse: our lanterns all began to dim until, after a few moments, they gave off only the faintest of glows. This had to be the work of dark magic, and the Spook immediately held up his hand, motioning us to halt. No sooner had we done so than the lanterns went out completely, plunging us into absolute darkness.

Was it a trick? I wondered fearfully. Had Horn lured us out here to our deaths?

I stood there, preparing myself for some sort of attack at any moment, but nothing happened.

‘Keep moving forward,’ Horn commanded from up ahead in the darkness. ‘We are almost there…’

We shuffled along very slowly; it was so dark that I couldn’t even see the Spook in front of me. But for the sound of his boots on rock, he could have vanished. Then I saw a faint glow.

As we got nearer, the luminosity grew; not in intensity but in size. It reminded me of the glowing sphere that had descended from the cavern roof to take a look at us. But whereas that had been small and yellow, this was red and immense. Neither was it a true sphere; it flexed and shifted its shape, as if under pressure from invisible internal or external forces.

From a distance it had appeared to have a definite outline, but as we approached, we saw that it was more like a mist in a forest dell, diffuse on its perimeter but far denser within. Already the abhuman was walking into it and becoming more indistinct. We followed – on my part, with increasing reluctance: I wondered if everybody else felt the same. The skin on my hands and face was tingling, my sense of danger increasing with every step I took. Then the abhuman came to a halt and turned to face us – just a horned silhouette against the radiance.

‘This is indeed the cache of Lucius Grim – I was right,’ said the Spook.

‘It presents no danger to you,’ Horn told him. ‘At least, not in itself. It’s the place where the buggane stores the life force that it steals from the living. It’s energy, that’s all – a vast store of animas reaped over centuries.’

‘Think of the hundreds of people it’s murdered.’ The Spook shook his head in disgust.

‘Not just hundreds – thousands upon thousands,’ said the abhuman. ‘Other bugganes have added to the cache; the process has gone on for centuries. This cavern is now a great source of energy and a meeting place for all those who are skilled in animism magic – not only shamans in spirit form, but Romanian witches. At present a coven of seven have temporarily projected their spirits from their distant homeland. They saw you enter the cavern and warned me of your whereabouts.’

The seven lights were now dancing high above our heads – they must be the witches’ spirits, I realized. I remembered reading an entry about such things in the Spook’s Bestiary. They were dangerous: a group like that could suck the life force from a human victim in minutes.

‘Come on then! Out with it,’ demanded the Spook, an edge of impatience in his voice. ‘What do you want?’

‘Revenge,’ said the abhuman, his cruel face contorting in anger. ‘I want revenge upon the witch who killed my master, Lord Barrule. I want her destroyed!’

‘Aye, we’d also like to put an end to her,’ said the Spook. ‘But have you brought us here just to tell us that? If so, it would have been better to let us go on our way.’

‘I needed to show you this – and to give you vital information,’ Horn went on. ‘Information that might help you to stop her in her tracks before she rules this whole island. You see, without realizing it, the witch is using my master’s thumb-bones as a conduit and drawing on the power stored here. And it will get worse, much worse. I’m using that same power and trying to resist her. But she is stronger than me, far stronger, and will soon have the buggane in her power. Then this vast reservoir will be at her disposal!

‘At the moment she knows nothing of this cache, but once she has made the buggane her creature, she will quickly learn the truth. Then she’ll realize what she’s capable of. And she won’t stop here. Eventually nations beyond our shores will be at risk.

‘My master was obsessed by gambling and never bothered to harvest more than a fraction of the magic that is available here; the witch is sure to seize it all and use it against those who cross her. You must act quickly before it’s too late!’

The Spook nodded. ‘We need to get those bones away from her – though that’s easier said than done. How long can you resist her? Just how long can you keep her away from the buggane?’

‘It’s impossible to say. All I know is that it’s getting harder with each day that passes,’ Horn replied. ‘There’s no time to waste. I’ll show you a tunnel which will take you up to the forest above. You needn’t face the witch’s bone-yard.’

As the abhuman led us across the darkness of the cavern, our lanterns flared back to their full brilliance. He guided us to a freshly dug tunnel before retreating back into the gloom. It went up at a steep angle, and it was indeed clear; within minutes we had emerged among the trees. It was still dark, but the sky was growing lighter on the eastern horizon and we could see Greeba Keep in the distance, lanterns gleaming on its battlements; the guard would be on full alert.

‘That tower’s too close for comfort,’ said the Spook. ‘The more distance we can put between it and us, the happier I’ll be.’

‘Nowhere’s safe now,’ Adriana said. ‘I’m heading home to Peel – I need to see to my mother. The shock of Father’s death may have been too much for her. You’re welcome to join me.’

‘We’re strangers to this island, so we’ll be glad to accept your invitation,’ said the Spook, ‘but first we’d better retrieve our bags.’