Duncan walked me back to my house, supporting me with his arm around my waist. He’d conjured clothes for both of us but they were soon so wet they didn’t do much good keeping us warm.

“There’s one thing I don’t understand,” I said, after a long silence.

“Hm … just one thing?”

I laughed. “No, actually there are many things, but one uppermost. Aelvesgold comes from Faerie, right?”

“Yes. Creatures from Faerie bring it with them when they come into this world.”

“Right, and witches use it to make magic …”

“Yes,” he said, holding back a sodden branch for me. The path was narrow here. I was conscious of my wet clothes brushing against him as I passed and I was glad it was too dark for him to see how my clothes clung to me, which was ridiculous considering that he’d seen me naked not half an hour ago.

“But Liz said the circle had a limited amount of it, and yet tonight I saw it all around me.”

“Yes, that’s because after you handled the Aelvestone you were filled with the stuff and drew even more of it to you. Think of the Aelvesgold as having a magnetic charge – the more you have inside you, the more you draw it to you.”

“Huh. Okay, so couldn’t there conceivably be enough Aelvesgold in this world to supply all the witches and fairies even if the door closes?”

Duncan shook his head. “Without replenishment from Faerie it would run out rather soon, unless …”

“Unless what?”

“Unless there was a creature that produced its own Aelvesgold even outside of Faerie.”

“You mean the way the undines lay an egg of Aelvesgold to protect their young?”

He made a face, either from pain or from squeamishness at talking about women’s reproductive cycles. “Not exactly. Undines only make enough extra Aelvesgold to protect their eggs. Once they lay their eggs they’re entirely depleted of Aelvesgold. If they don’t go back to Faerie they’ll wither and die. No, I’m talking about a creature that makes its own Aelvesgold in this world and never needs to go back to Faerie. If there were a race of creatures like that they would rule the whole world and we wouldn’t have to worry about the door closing. I could do some research into it today and return this evening.”

We’d reached my back door. “What about Lorelei?” I asked. “We have to tell Liz and the others that she’s here in Fairwick.”

“I’ll alert your dean to the situation. You should try to get some rest. Transformations take a lot out of you.”