"We get all kinds of stuff coming through here on a regular basis, old sport, things you wouldn't believe, even for the Nightside. Some silly sod put his soul up for auction just the other week, but it didn't make the reserve. Ah yes, I've seen it all come and go, and known more than my fair share of tears and curses. Property is the curse of the thinking classes. Now, Taylor, old boy; the Hall is of course surrounded by heavy-duty wards and protections at all times, protecting us from fire, theft, substitution, and any and all outside influences, and the whole place is guaranteed neutral ground by the Authorities themselves, and respected as such even by really hard cases like the Collector. As I understand it, the Hall was the cause of so many disputes by so many high rollers that the Authorities just stepped in and took over the business themselves, to make sure all deeds were kept and honoured ... So we should be safe enough..."

"But?" I said.

"But, today we're auctioning something rather special, even for us. That's why you're here, old thing. If everything does all go to Hell in a handcart, and I for one wouldn't be at all surprised if it did, you get to stick your hand up and say, Stop thief. What you do after that is your problem. Only don't look to me for help, because I shall have headed for the nearest exit. And don't look to the bears, either. They mean well, but they've only got sawdust where their balls should be. If all else fails, I suppose you can always use your famous gift to track down wherever the thief's taken it..."

"Why did you hire me?" I asked, genuinely interested.

Grave sniffed loudly. "Our insurance people insisted we hire someone, and you were the best... our budget could stretch to."

I was still looking for a response to that when we were approached by a familiar figure. It was Deliverance Wilde, fashion consultant and style guru to the Faerie of the Un-seeli Court. Tall, loudly Jamaican, sharp and bitter and a defiant chain-smoker. If anyone ever found the nerve to object, she blew the smoke into their faces. She was currently wearing an elegantly tailored suit of a vivid lavender shade, which contrasted interestingly with her blue-black skin, topped by a very feathery hat. I raised an eyebrow at the new look, but as always Wilde got her retaliation in first.

"Don't show your ignorance, darling. Lavender is this season's colour, whether it likes it or not."

She struck a studiedly casual pose before me, head tilted back to better show off her high cheekbones and sensual mouth. Deliverance Wilde treated the whole world like a catwalk. Yet her eyes had trouble meeting mine, and the hand holding her cigarette wasn't as steady as it might have been. Wilde was nervous about something. Now, it might just have been the strain of meeting me. I do tend to make people nervous; it's part of my carefully crafted reputation. But Wilde wasn't really focussed on me, or even Grave. Instead, she glared about the Auction Hall, shooting quick puffs of smoke in every direction.

"I always hate coming back to the Nightside," she said abruptly. "Vulgar, darlings, utterly vulgar. I prefer to spend my time with the Faerie. They're so ... delightfully shallow and superficial."

Lot you know, I thought, but had the sense not to say it aloud. Wilde had been known to stub her cigarette out on people who annoyed her.

"I only come back here to attend the fashion shows and stock up on ciggies," she continued remorselessly. "And to carry out the odd spot of business, of course." She looked at me directly for the first time. "I'm glad you're here, John. It means the Auction Hall is taking this event seriously. As they should. I have got my hands on ... something rather special."

Lucretia Grave snorted loudly. "I should say so, old dear. Unique, priceless, and bloody dangerous with it. Some things should be left alone, or at the very least prodded with a stick from a safe distance,"

"Would somebody please tell me what it is we're talking about?" I said, and something in my voice made them both sit up and take notice. Wilde took a last drag on her cigarette, dropped it on the floor, and ground it out under her boot. Grave glared at her. Wilde immediately lit up another, on principle, and fixed me with a thoughtful gaze.

"I have hit the big time at last, darling. I found my little prize accidentally, while looking for something else, but then, isn't that always the way? I was off on my travels, looking for Something Different with which to pique the interest of those notoriously fickle and demanding Faerie, and I ended up in Tokyo, investigating reports of this marvellous new firm that specialised in creating these utterly amazing bonsai volcanoes, complete with regular eruptions and lava flows. But by the time I got there, the firm was gone, and their shop was just this big smoking hole in the ground. I could have told them more bang for your buck was a really bad idea for a slogan ... Anyway, I got side-tracked to China, where I found... that."

And she indicated one of the smaller display cases with a dramatic gesture and a sprinkling of ash because she'd forgotten the cigarette in her hand. She muttered a series of baby swear words and brushed the ash off the top of the case, while I leaned forward for a closer look. Behind the glass was a single butterfly, not particularly big or small, or especially pretty. In fact, it looked distinctly ordinary. It hung in mid air, in mid-flight, wings extended, surrounded by the faint shimmer of a stasis field. The butterfly had been frozen in a moment of Space and Time, like an insect preserved in amber. I looked back at Wilde, but again she got in first while I was still raising an eyebrow.

"Yes, it's rare, but not in the way you think. The explanation's a bit complex, but try and keep up. Chaos theory says that if a butterfly flaps its wings over China, we end up with a storm over America. Since everything in the world is connected, or at least on speaking terms. So, if you could identify and track down that particular butterfly ... Well, I have, and there it is. The little troublemaker. A wonderfully unique item, which I intend to let go for an equally unique price. Oh, the Collector is going to be so jealous!"

(Wilde and the Collector had a thing going once. It didn't work out. No-one ever thought it would, but you just can't tell some people.)

"The butterfly theory is nothing new, really," said Grave, in her most academic and tweedy voice. Auctioneers always sound like failed scholars. Probably because most of them are. "The ancient Romans had people called Augurs who could predict the future by studying the flight of birds."

Wilde gave her a withering look. "They also had a tendency to cut open goats, then accuse people of treason over which way the goat's liver was pointing. And give themselves lead poisoning with their choice of plumbing materials."

"Let us all make a valiant effort to stick to the point, please," I said. "Isn't the whole butterfly thing just a metaphor? There isn't a real butterfly, as such."

Wilde hit me with her most withering smile. "Metaphors can be as real as anything else in the Night-side, darling. Symbols can have their own identity here. So, whatever lucky person takes possession of this butterfly at auction will possess the power to identify all such butterflies; the first domino in the line that will produce future events. The owner should then be able to predict and possibly even control the way the future turns out. The possibilities are endless! In theory, anyway. Trust me on this, John darling; I am going to be rich, rich, rich!"

"If it's so potentially powerful, why are you so ready to give it up?" I asked.

Wilde struck her best Why am I beset by fools of no vision pose. "John. Darling. I am not stupid enough to try and keep anything this earth-shattering for myself. I'd have to spend all my time fighting off major players who wanted to take it away from me. And you can bet the Faerie wouldn't deign to get involved, the ungrateful little shits. No, an auction, on famously neutral ground, is the best way to make a substantial profit on this little beauty." She blew a kiss at the butterfly in its case. "And then I shall take all the money and run, all the way back to the Unseeli Court, and not show my head again until the last of the shooting's died down."