“You are a ghost. I know you are. So, what, am I psychic?”

My head is prickling all over as this revelation hits me. I feel a bit shivery. I can talk to the dead. Me, Lara Lington. I always knew there was something different about me.

Think of the implications. Think what this means! Maybe I’ll start talking to more ghosts. Lots of ghosts. Oh my God, I could have my own TV show. I could go around the world. I could be famous! I have a sudden vision of myself on a stage, channeling spirits while an audience watches avidly. With a surge of excitement, I lean across the table.

“Do you know any other dead people you could introduce me to?”

“No.” Sadie folds her arms crossly. “I don’t.”

“Have you met Marilyn Monroe? Or Elvis? Or… or Princess Diana? What’s she like? Or Mozart!” I feel almost dizzy as possibilities pile into my head. “This is mind-blowing. You have to describe it! You have to tell me what it’s like … there.”

“Where?” Sadie tosses her chin.

“There. You know…”

“I haven’t been anywhere.” She glares at me. “I haven’t met anybody. I wake up and it’s as though I’m in a dream. A very bad dream. Because all I want is my necklace, but the only person who can understand me refuses to help me!” She looks so accusing, I feel a surge of indignation.

“Well, maybe if you didn’t come along and ruin everything, that person might want to help you. Did you think of that?”

“I didn’t ruin everything!”

“Yes, you did!”

“I taught you how to eat an oyster, didn’t I?”

“I didn’t want to know how to eat a bloody oyster! I wanted my candidate not to walk out!”

For a moment, Sadie looks cornered-then her chin juts out again. “I didn’t know he was your candidate. I thought he was your lover.”

“Well, my business is probably sunk now. And I can’t afford any of this stupid food. It’s all a disaster and it’s all your fault.”

Morosely, I reach for another oyster and start poking at it with my fork. Then I glance at Sadie. All her spirit seems to have evaporated, and she’s hugging her knees with that droopy-headed-flower look. She meets my eyes, then drops her head down again.

“I’m sorry.” Her voice is barely above a whisper. “I apologize for causing you so much trouble. If I could communicate with anyone else, I would do so.”

Now, of course, I feel bad.

“Look,” I begin. “It’s not that I don’t want to help-”

“It’s my final wish.” As Sadie looks up, her eyes are dark and velvety and her mouth is in a sad little O shape. “It’s my only wish. I don’t want anything else; I won’t ask you for anything else. Just my necklace. I can’t rest without it. I can’t-” She breaks off and looks away as though she can’t finish the sentence. Or doesn’t want to finish it, maybe.

I can tell this is a bit of a sensitive area. But I’m too intrigued to let it go.

“When you say you ‘can’t rest’ without your necklace,” I venture delicately, “do you mean rest as in sit down and feel relaxed? Or do you mean rest as in pass on to … there?” I catch her stony gaze and amend hastily, “I mean, the Other… I mean, the Better… I mean, the After-” I rub my nose, feeling hot and bothered.

God, this is a minefield. How am I supposed to put it? What’s the politically correct phrase, anyway?

“So… how does it work, exactly?” I try a different tack.

“I don’t know how it works! I haven’t been given an instruction pamphlet, you know.” Her tone is scathing, but I can see an insecure flash in her eye. “I don’t want to be here. I’ve just found myself here. And all I know is, I need my necklace. That’s all I know. And for that… I need your help.”

For a while there’s silence. I swallow another oyster, uncomfortable thoughts jabbing at my conscience. She’s my great-aunt. This is her one and only last wish. You should make an effort with someone’s one and only last wish. Even if it is totally impossible and stupid.

“Sadie.” At last I exhale sharply. “If I find your necklace for you, will you go away and leave me in peace?”

“Yes.”

“For good?”

“Yes.” Her eyes are starting to shine.

I fold my arms sternly. “If I look for your necklace as hard as I can but can’t find it because it was lost a zillion years ago or, more likely, never existed… will you still go away?”

There’s a pause. Sadie looks sulky.

“It did exist,” she says.

“Will you?” I persist. “Because I’m not spending all summer on some ridiculous treasure hunt.”

For a few moments, Sadie glowers at me, clearly trying to think of some put-down. But she can’t.

“Very well,” she says at last.

“OK. It’s a deal.” I lift my champagne glass toward her. “Here’s to finding your necklace.”

“Come on, then! Start looking!” She darts her head around impatiently, as though we might start searching right here and now in the restaurant.

“We can’t just go randomly looking! We have to be scientific.” I reach into my bag, pull out the necklace sketch, and unfold it. “All right. Think back. Where did you last have it?”

Fairside Nursing Home is in a leafy residential road: a redbrick, double-fronted building with net curtains in every single window. I survey it from the other side of the road, then turn to look at Sadie, who has been following me in silence ever since Potters Bar station. She came with me on the tube, but I barely saw her: She spent the whole time flitting along the carriage, looking at people, popping up to ground level and down again.

“So, that’s where you used to live,” I say with an awkward brightness. “It’s really nice! Lovely… garden.” I gesture at a couple of mangy shrubs.

Sadie doesn’t answer. I look up and see a line of tension in her pale jaw. This must be strange for her, coming back here. I wonder how well she remembers it.

“Hey, how old are you, anyway?” I say curiously, as the thought occurs to me. “I mean, I know you’re a hundred and five really. But now. As you are… here.” I gesture at her.

Sadie looks taken aback by the question. She examines her arms, peers at her dress, and thoughtfully rubs the fabric between her fingers.

“Twenty-three,” she says at last. “Yes, I think I’m twenty-three.”

I’m doing mental calculations in my head. She was 105 when she died. Which would mean…

“You were twenty-three in the year 1927.”

“That’s right!” Her face suddenly comes alive. “We had a pajama party for my birthday. We drank gin fizzes all evening and danced ’til the birds started singing… Oh, I miss pajama parties.” She hugs herself. “Do you have many pajama parties?”

Does a one-night stand count as a pajama party?

“I’m not sure they’re quite the same-” I break off as a woman’s face glances out of a top-floor window at me. “Come on. Let’s go.”

I head briskly across the road, up the path to the wide front door, and press the security buzzer.

“Hello?” I call into the grille. “I don’t have an appointment, I’m afraid.”

There’s the sound of a key in a lock, and the front door opens. A woman in a blue nurse’s uniform beams at me. She looks in her early thirties, with her hair tied back in a knot, and a plump pale face.

“Can I help you?”

“Yes. My name’s Lara, and I’m here about a… a former resident.” I glance at Sadie.

She’s gone.

I hurriedly scan the whole front garden-but she’s totally disappeared. Bloody hell. She’s left me in the lurch.

“A former resident?” The nurse prompts me.

“Oh. Er… Sadie Lancaster?”

“Sadie!” Her face softens. “Come in! I’m Ginny, senior staff nurse.”

I follow her into a linoleum-floored hall smelling of beeswax and disinfectant. The whole place is quiet, apart from the nurse’s rubber shoes squeaking on the floor and the distant sound of the TV. Through a door I glimpse a couple of old ladies sitting in chairs with crocheted blankets over their knees.