The hotel job took a while, but was straightforward in the end. Or rather, it was straightforward, right up until the end.

Twin brothers, middle-aged men, had died in a gas leak in the original hotel building, a hundred years before. Now their twin ghosts roamed the upper floors, tormenting everyone who had hoped not to choke to death in their sleep.

There was an interesting twist. The men had died in a mezzanine floor which no longer existed, meaning they floated along with their bodies visible from either just the waist up, in the floor, or the waist down, legs dangling from he ceiling. It was rather disconcerting.

Quill and I dodged them up and down corridors in the musty old hotel, and searched for their source with no luck.

I asked the skull for help, but it gave no answer. There was no sign of its familiar green glow, or the ghost of the youth.

It must still be sulking, which was annoying, because at times like this it was truly useful.

Eventually I stopped in an upstairs corridor, held the identical plump ghosts at bay - protruding from the carpet in front of me - and questioned them about their deaths.

I had cast an iron circle behind me, ready to step into should the ghosts attack, but to hear them clearly, I needed to be out of it. "Get inside," I said to Quill, who had his goggles on.

"I'm ok."

"Don't be stupid." I have no time for niceties at work. "Get in, Quill."

I quizzed the twins and among their repetitive ramblings, caught something about a gas pipe. "Ah! Of course..."

The ghosts, sensing my momentary distraction, surged forward.

I jumped into the circle, pulling Quill in with me. He swore.

"I got it," I said. "The source is the gas pipe that killed them. But where is it?"

"No idea." He handed me salt bombs, and I lobbed them at the ghosts and tried to think what I knew about gas plumbing. Not a lot, was my conclusion.

It was Quill who found the source. After we left the circle to begin the search again, he had a blast of inspiration and led me straight to the stairs between the two current hotel floors. There was a length of thick, flat old cable that vanished into a tiny cupboard, the door of which was painted shut. "This was on the demolished mezzanine," he said."It's all that's left. Bet the source is in there. Either that or a dangerously leaky gas pipe. Let's find out!"

"Give me the wrench."

Quill said, "I'll do it." He took the wrench in his hands and with great relish bashed the little door in.

"Aha!" I started taking out a silver net. There it was - an old stopcock wheel, disconnected, lying in this forgotten old service cupboard.

"Lucy," said Quill, "forgot to mention, they're back."

I swung round. The pudgy figures of the two spirits loomed close to Quill, perilously close -

I raised my rapier and sliced at the nearest one. "I've got this. You do the net."

I tossed him the net, and he dropped it. "For god's sake! Here." I passed him another net. "Hurry up, it's two against one."

"Right."

I advanced down the stairs towards the ghosts, creating a pattern of entrapment with my rapier, a complicated shape in the air which Lockwood had taught me, and he and I had spent hours practising, our swords in perfect unison in the basement at Portland Row.

The twins recoiled from the metal, then swirled back at me. They seemed stronger, and I realised in irritation that they were feeding off my nostalgic emotions. "Dammit. Where are you with the net, Quill?"

I forced the ghosts down the stairs a little way.

"Can't get the net out," he said behind me.

"For pity's sake! Ok, swap places."

"No, I've got it." But when I glanced round, he stood there holding it, not throwing it over the source, not doing anything useful at all.

A ghost swiped at me, and I cut through it, splattering ectoplasm. "For god's sake!"

As they advanced, I climbed backwards uo the steps, slicing and whirling with the rapier in one hand, my other retrieving a silver net and, without looking, shaking it free of its packet. The twins were nearer, dodging my blade, reaching out eagerly to touch me. I arrived at the level of the little cupboard, whirled and flung the net over the stopcock, and the ghosts dissolved and vanished.

I slumped down and sat on the steps. "What the hell was that, Quill? They almost got me, where were you?"

He looked horrified. He flung his net away. "I couldn't," he said, and then he doubled over and threw up, all the way down the stairs.

"I'm going to stop putting two scoops in the coffee," I said later that night. "Calm down!"

I had emerged from a much-needed shower, to find Quill bouncing around my flat. "I've never seen in here before," he said, opening random cupboards and gazing at the contents. "So this is what's on top of the wardrobe!"

"You're being very weird..."

"Am I? Sometimes it's just so good to be alive, you know?"

He bounded over and patted my arm.

"Are you staying?" I asked. He never usually stayed at mine - my bed was up against a wall, so was not easy to get in and out of with two of you. And, honestly, I could use a break. I had some thinking to do, and I had promised the skull I would talk to it. Not that it had said a dicky bird all night.

"Maybe, maybe." He was still dancing about, touching stuff.

"If you're not staying, you'd better get going." I opened my bag. "Where's the skull?"

"The what?"

"The skull. It was in my bag." I rummaged, first quickly, then thoroughly. Then I upended the bag and picked through every item. But the skull was gone.

I clutched at my head. "Oh god, where is it?"

Quill came to look. "Maybe it's good riddance?"

"No! If I've lost the source... I've lost the ghost. It must be here."

I tore through the flat, searching.

"Leave it," said Quill. "It'll turn up."

"I can't. If I've lost it I don't know what I'll do."Alternating between fury and despair, I raked through my possessions.

At last Quill said, "I am staying."

"Ok." But you know what it's like when you've lost something - you can't stop looking.

At last I forced myself to put on pyjamas and get into bed. "Are you joining me then?"

I hadn't meant it to sound snarky, but luckily, Quill was so wired he didn't notice.

"I'm not tired," he said like a toddler who's been told to go upstairs. "I'm wide awake!"

"Well, you sit up then, read a book. I need to sleep."

"All right."

I lay there while at the table, he turned page after page in my casebook. I kept still, and thought about nothing for as long as I could manage. And then I thought about Lockwood.

Why had he rung me in the middle of the night?

I'd forgotten to call him and say about the ghost and its seeming ability to roam. Bother. And now the skull was missing.

I had to speak to him. Not just about that. We used to be such friends. More than friends, obviously. We had been in love.

I turned my face away from Quill and closed my eyes.

Memory came unbidden. The times Lockwood and I had staggered back triumphant from a night battling ghosts. We would tumble, battered and ragged, into Portland Row for tea and toast, and then, still laughing, climb the stairs to his immaculate bedroom... The way we kissed, as if the world was ending around us. How we sprawled on his bed, looking into each other's eyes, watching all the love and wonder there, amazed that it was ours.

-Lockwood's deft fingers, unfastening my necklace. He ran his thumb along my cheek, then kissed me as if I was the most precious thing he'd ever known.

-Lockwood in shirt sleeves, lounging but alert as I trailed my hand over his chest. Me, taking his hand and kissing his fingertips while our bare feet twined together. Me, shy to do it but murmuring his first name... His hand on my waist, sliding up, and the way his gaze flickered as his palm traced a path over my ribs.

I squeezed my eyes tight shut. We had been so young. We were right to take things slow, not to rush into anything we might regret. My god. How mature you are, at sixteen.

Damn, damn, damn.

I couldn't have these thoughts with Quill six feet away. I took a long breath, and made myself think of nothing again, and finally fell asleep.

I was woken, some time later, by Quill crawling into bed beside me. He was undressed, or rather, in pyjamas, and he was positioning himself on the very edge of the bed.

"You can budge up," I said, flinging my arm over him. "There's room."

He squeaked as I pulled him against me. With his back to me, he lay rigid and awkward. "Night then."

"Night..." I kissed the back of his neck and lay down. It was ok. I didn't have to try to solve my boyfriend problem, or more accurately, my Lockwood problem, right now. Quill was here, and seemed recovered from his bizarre evening.

I drifted for a bit, enjoying the simple fact of his warmth next to me.

I'm in her bed, with her.

I opened my eyes. "Quill?"

Nothing. He was asleep. His mouth twitched.

Well, that was weird. Then I remembered the lost skull. Had it spoken, and woken me? "Skull," I whispered. "Are you there?"

No reply. Quill murmured, turned towards me. In the flickering half light of the ghost lamps outside, he almost seemed to glow.

I sighed, without being able to explain why, and went back to sleep.