'Who are you?' I asked, pointing my gun at her.

She lowered the mirror, smiled and looked at the pistol.

'Dear me!' she exclaimed. 'Always the woman of action, aren't you?'

'What am I doing here?'

'You really don't know, do you?'

'No,' I replied, lowering the gun. I couldn't remember any facts but I could feel love, and loss, and frustration, and fear. The woman was linked to one of these but I didn't know which.

'My name,' said the young woman, 'is—'

She stopped, and smiled again.

'No, I think even that is too much.'

She rose and walked towards me.

'All you need to know is that you killed my brother.'

'I'm a murderer?' I whispered, searching in my heart for guilt of such a crime and finding none. 'I … I don't believe you.'

'Oh, it's true,' she said, 'and I will have my revenge. Let me show you something.'

She took me to the window and pointed. There was another flash of lightning and the view outside was illuminated. We were on the edge of a massive waterfall which curved away from us into the darkness. The ocean was emptying over the edge; millions of gallons every second, falling into the abyss. But that wasn't all. In another flash of lightning I could see that the waterfall was rapidly eroding the small island on which the lighthouse was built — as I watched, the first piece of the rocky outcrop fell away noiselessly and disappeared into space.

'What's happening?' I demanded.

'You are forgetting everything,' she said simply, sweeping her hands in the direction of the room. 'These are a just a few of your memories I have cobbled together — a last stand, if you like. The storm, the lighthouse, the waterfall, the night, the wind — none of them is real.' She walked closer to me until I could smell her perfume. 'All this is merely a representation of your mind. The lighthouse is you; your consciousness. The sea around us your experience, your memories — everything that makes you the person you are. They are all draining away like water from a bath. Soon the lighthouse will topple into the void and then—'

'And then?'

'And then I will have won. You will remember nothing — not even this. You will relearn, of course — in ten years you might be able to tie your own shoelaces. But for the first few years the only decision you will have to make is which side of your mouth to drool out of …'

I turned to leave but she called out:

'You can't run. Where will you go? For you, there's nowhere else but here.'

I stopped at the door and turned back, raised my gun and fired a single shot. The bullet whistled through the young woman and impacted harmlessly on the wall behind.

'It will take more than that, Thursday.'

'Thursday?' I echoed. 'That's my name?'

'It doesn't matter,' said the young woman. 'There is no one you can remember who will help you.'

'Doesn't this make your victory a hollow one?' I demanded, lowering my gun and rubbing my temple, trying to recall even a single fact.

'Ridding your mind of that which you value most was the hard bit,' replied the woman. 'All I had to do then was to invoke your dread, the memory that you feared the most. After that, it was easy.'

'My greatest fear?'

She smiled again and showed me the hand mirror. There was no reflection, only images that flashed past anonymously. I took the mirror and peered at it, trying to make sense of what I saw.

'These are the images of your life,' she told me. 'Your memories, the people you love, everything you hold dear — but also everything that you've ever feared. I can modify and change them at will — or even delete them completely. But before I do, I'm going to make you view the worst once more. Gaze upon it, Thursday, gaze upon it and feel the loss of your brother one last time!'

The mirror showed me the image of a war long ago, the violent death of a soldier who seemed familiar, and I felt the pain of loss tearing through me. The woman laughed as the images repeated themselves, this time clearer, and more graphic. I shut my eyes to block the horror, but opened them again quickly in shock. I had seen something else, right at the edge of my mind, dark and menacing, waiting to engulf me. I gasped, and the woman felt my fear.

'What is it?' she cried. 'There is something I have missed? Worse than the Crimea? Let me see!'

She tried to grasp the mirror but I let it drop. It shattered on the concrete floor and we heard a muffled thump as something struck the steel door five storeys below.

'What was that?' she demanded.

I realised what I had seen. Its presence, unwelcome for so many years in the back of my mind, might be just what I needed to defeat her.

'My worst nightmare,' I told her, 'and now yours.'

'But it can't be! Your worst nightmare was the Crimea, your brother's death — I know, I've searched your mind!'

'Then,' I replied slowly, my strength returning as the woman's confidence trickled away, 'you should have searched harder!'

'But it's still too late to help you,' she said, her voice quavering. 'It will not gain entry, I assure you of that!'

There was another loud crash; the steel door on the ground floor had been torn from its hinges.

'Wrong again,' I said quietly. 'You asked it to attend, and it came.'

She ran to the stairs and yelled:

'Who is there? Who are you? What are you?'

But there was no reply; only a soft sigh and the sound of footfalls on the stairs as it climbed slowly upwards. I looked from the window as another section of the rocky island fell away. The lighthouse was now poised on top of the abyss and I could see straight down into the dizzying depths. There was a tremor as the foundations shifted; the lighthouse flexed and a section of plaster fell from the wall.

'Thursday!' she yelled out pitifully. 'You can control it! Make it stop!'

She slammed the door to the staircase, her hands shaking as she hurriedly threw the bolt.

'I could hide it if I chose,' I said staring at the terrified woman, 'but I choose not to. You asked me to gaze upon my fears — now you may join me.'

The lighthouse shifted again and a crack opened in the wall, revealing the storm-tossed sea beyond; the arc light stopped rotating with a growl of twisted metal. There was a thump at the door.

'There are always bigger fish, Aornis,' I said slowly, suddenly realising who she was as my past began to reveal itself from the fog. 'Like all Hades, you were lazy. You thought Anton's demise was the worst thing you could dredge up. You never looked farther. Hardly looked into my subconscious at all. The old stuff, the terrifying stuff, the stuff that keeps us awake as children, the nightmares we can only half glimpse on waking, the fear we sweep to the back of our minds but which is always there, gloating from a distance.'

The door collapsed inwards as the lighthouse swayed and part of the wall fell away. An icy gust blew in, the ceiling dropped two feet and electricity sparked from a severed cable. Aornis stared at the form lurking in the doorway, making quiet slavering noises to itself.

'No!' she whined. 'I'm sorry, I didn't mean to disturb you, I—'

I watched as Aornis' hair turned snow white but no scream came from her dry throat. I lowered my eyes and turned to the door, seeing out of the corner of my eye only a vague shape advancing towards Aornis. She had dropped to her knees and was sobbing uncontrollably. I walked past the shattered door and down the stairs two at a time. As I stepped outside, the outcrop shivered again and the conical roof of the lighthouse came wheeling down amid masonry and scraps of rusty iron. Aornis found her voice, finally, and screamed.

I didn't pause, nor break my pace. I could still hear her yelling for mercy as I climbed into the small jolly-boat she had kept for her escape and rowed away across the oily black water, her cries drowned out only as the lighthouse collapsed into the abyss, taking the malevolent spirit of Aornis with it.