Freaky, weird and very disturbing. My consciousness ricocheted back and forth between my heads, me seeing me seeing me, and the only coherent thought I could manage was, Is that really what I look like? I concentrated, bearing down hard, and then it occurred to the me looking in from outside that I had to be the original because I was still wearing the Gemini Duplicator ring. I held up my hand to prove it, and the me standing inside held up my hand. We both had rings. I decided enough was enough, and both of me squeezed my fingers against the ring. And just like that there was only me, standing in the open doorway. Air rushed in to fill the vacuum where the other me had been standing just a moment before, like an explosion in reverse. I rocked on my feet, struggling to reconcile two sets of memories from the same period, but it all came together surprisingly easily. I hurried forward, and closed the door quietly behind me.

I put my back to the door and scowled at the long empty hall stretching away before me. My skin crawled in anticipation of sudden alarms, but there was nothing. I couldn't quite believe how easy they were making this for me. Powerful protective shields are all very well, but you can't beat the human touch when it comes to spot ting intruders. In the end I just shrugged, and allowed myself to breathe a little more easily. I might not be able to call up my armour here, but my torc's basic nature should still be enough to hide me from any and all inner surveillance systems. The Immortals might or might not have had systems in place to detect the presence of old torcs, but I was betting they didn't have anything that could deal with the new strange matter torcs. The Immortals might have infiltrated the Droods, but they didn't understand Ethel.

Nobody did.

I pulled up my collar a little, to hide the torc from a casual glance, and strode down the long hall like I was thinking of renting it out. When penetrating an enemy stronghold, confidence is everything. Look like you belong there, and no one will challenge you. So far, Castle Frankenstein was everything it should be: old stonework, marvellously carved and ornate; standing suits of armour, burnished to within an inch of their lives; elegant medieval tapestries and hanging cloths; and rows of dark frowning portraits. Old Frankensteins or old Immortals, I didn't know or give a damn. It was all very Gothic, apart from the electric light chandeliers and the hidden central heating, the benefits of which I was currently enjoying after so long in the cold, cold night.

The Castle so far reminded me a lot of Drood Hall. Of long and not forgotten history, held over into the modern day. The Immortals were as old as we were, and the two of us had a lot more in common than I liked to admit. Two ancient families, their present still dominated by their past, who never threw anything away. The Immortals were the one thing we'd always feared the most, our darkest nightmare: the Anti-Droods. Everything we could have been, if not for our role as shamans, defenders of the Human tribe. Be sure your nightmares will find you out…

I stopped, some distance down the hall, and looked thoughtfully about me. It had just occurred to me that everything in the hall was perfectly clean, polished, and waxed… For all the Gothic look, there wasn't a cobweb in sight. And I had to wonder about that. Surely the Immortals wouldn't allow humble cleaning staff to enter their secret sanctorum? Who could they trust, to come in and do for them? They couldn't employ the local townspeople as servants; like everyone else, the locals had been programmed to see Castle Frankenstein as nothing more than ancient ruins. And surely the great and secret masters of the world wouldn't lower themselves to get out the bucket and mop and do it themselves?

A quiet, subtle sound caught my attention, and I looked sharply round. And there behind me was a short, squat creature, almost as broad as it was tall, wearing simple blue overalls, with a bucket and mop… slowly but thoroughly cleaning up the trail of scuffed muddy footprints I'd left behind me. (I couldn't believe I'd done that. Footprints? I was far too used to my armour looking after me.) I recognised what the cleaner was; I'd seen his people at work, in and around London. This was a kobold, one of the underfolk, from under the ground. Ancient inhabitants of the Hidden World, like Pixies, Brownies, Trolls. Mostly gone now, to other more hospitable realities, like the Elves. But the kobolds I'd encountered before had been proud, hardworking creatures, always paid the best rates because they were the only ones brave enough to do the really hard work. So what was a kobold doing here, working as a cleaner for the Immortals?

I strolled back to the creature, smiling on it in what I hoped was a friendly and not at all threatening way. It looked up from its work, but didn't stop, slowly and methodically removing all traces of my presence. Up close, it looked more like a Neanderthal than anything else: brutal but still basically humanoid, heavy browed and heavy boned, with a wide face, no chin, and sharp crafty eyes. It nodded briefly to me.

"You shouldn't be here," it said, in a low growling voice. "Come to take on the Immortals, in their own place of power, have you? Be welcome, fool. Try to die well, with honour."

"I'm a Drood," I said calmly. "Other people do the dying."

The kobold looked at me sharply. "Then you should know better than to be here. You might stand a better chance than most, but you're still a damned fool to break into Castle Frankenstein. And a doomed one. Doomed… No one can beat the Immortals. They go on forever, because they can."

"Everything comes to an end eventually," I said, with a confidence I wasn't entirely sure I felt. "You're a kobold, aren't you? What are you doing here, working for the Immortals?"

"Kobold. Yes. Very old people. We were here before the Immortals. Before this Castle. We were miners, then. Digging deep, deep under the earth. Left to ourselves, and liked it that way. We stayed on after so many of the other underfolk left, because no one bothered us, down in the depths of the earth. There was still a lot of gold left, and we like gold. They built a Castle above us, and we didn't care. Until he came. The one everyone talks about. The Frankenstein, the living god of the scalpel. He discovered us, brought us up into the light, made us his servants. And after he left the Immortals moved in, and they made us their slaves. Put these yokes upon us."

He lifted his head to show me the cold iron collar around his throat, etched with runes. He was careful not to touch it.

"The Immortals own us now. Generations of kobolds have been born in this cold stone tomb, never to know the comforts of the dark, and the earth, the mines and the gold. Once there were thousands of us, then hundreds, now less than one hundred. We do not belong in this world. And we were never meant to be slaves."

"I can rip that yoke right off you," I said. "If you want."

"No you can't. The yoke will kill me, rather than let me go. The Immortals never let go of anything they own."

"Then I will bring down the Immortals," I said. "And make them free you. All of you."

"Why should you?" said the kobold. "Why should you give a damn about the underfolk? You're human."

"Because I'm a Drood," I said. "And that's what Droods do."

The kobold leaned forward, fixing me with its cold, bright eyes. "Kill them all, Drood. They've earned it."

I walked the whole length of the hall, looking vaguely around for a map of some kind, or a floor plan of the Castle. Preferably something set out neatly on a wall, with YOU ARE HERE, and all the important areas clearly marked. But of course, there was nothing like that. The people who lived here didn't need a map, and they actively discouraged tourists. I had no idea of what I was looking for, and where I should be going; that's what happens when you plan a mission in a hurry. All my thoughts had centred around how I was going to get in, and not enough about what I'd do afterwards. We should have got more specific information out of Rafe, but I was too impatient. Now I was here, I wanted information, which meant records, which meant computers. While I was standing at the foot of a long sweeping set of stairs, at the end of the hall, looking vaguely around in search of inspiration, a side door opened, and out came a teenager with long floppy hair, in sweatshirt, jeans and trainers. He stopped abruptly, and looked at me.