The figure doesn’t move. It’s utterly still. I watch, and as I do it seems to recede somehow, into the shadows. There, yet not there.

I turn and wake my husband. ‘Hugh. Come here. Look. He’s here again.’

Reluctantly he gets up. The street is empty.

Maybe Hugh’s right. Maybe I am being paranoid.

‘Hugh thinks I’ve lost my mind,’ I tell Anna. We’re on Skype, I’ve finished adding some images to my website, tidying things up. Her face is in the window in the corner of my screen.

‘Could it just be someone walking their dog?’

‘There’s no dog.’ She begins to say something, but the video freezes and I don’t hear it. A moment or so later it resumes and I carry on. ‘He’s standing outside my house. It creeps me out. If I turn away, to fetch Hugh or whatever, he’s always disappeared when I turn back.’

‘It might just be some weirdo.’

‘It might, I guess.’

‘Have you talked to Adrienne?’

‘No,’ I say. I’d meant to the other night, but was worried she already thought I was crazy.

‘What are you going to do?’

I tell her I don’t know. ‘But it feels so real. I swear. I’m not crazy.’

‘Of course not,’ she says. ‘I didn’t think that for a second. Also, it’s a pretty logical response to what’s happened.’

I’m relieved. Even if Anna is humouring me, at least she’s doing that rather than trying to convince me I’m mistaken, or insane.

‘How’re things with that guy? The one you’ve been messaging. The one you think might have something to do with Kate.’

‘Lukas?’

Should I tell her? Or will she just tell me to give the information to the police and then walk away?

‘Not sure,’ I say. I give her some details. More than I gave Adrienne, but not everything. ‘We’re messaging occasionally. There’s something about him. Something I can’t quite put my finger on. It’s probably nothing …’

Is it, though? He’s still pursuing me. Or I’m pursuing him; I can’t tell. Either way, I’ve turned my camera on, too, now. Last night. Just for a moment, less than a minute. But I’ve let him see me.

Yet I don’t tell her that.

‘Well, I heard back from that guy I messaged. The one from Kate’s list? Harenglish.’

‘You did?’

And you didn’t tell me? I think, I guess he must have had nothing to do with it.

‘What did he say?’

‘Nothing much. But he said he isn’t looking to meet people, not in real life. He’s online for a bit of fun. Sexy chats, he said. But online only. He loves his wife too much to risk anything else.’

‘You believe him?’

‘Yes. Yes I do.’

It’s the day of Carla’s party. She lives miles away, halfway to Guildford. Hugh drives, Connor sits behind me, listening to music on his iPod, far too loud. Last year we’d all enjoyed the day; I’d taken a salad I’d made – grilled aubergines, a salmon with preserved lemons – and even bought a new dress. Connor had got on well with the neighbour’s children, Hugh had enjoyed relaxing with his colleagues. Now, I don’t want to be here; I’d had to be persuaded. ‘It’ll be fun,’ said Hugh. ‘Connor will get to see his friends, and it’ll be a chance for you to show him how well you’re coping.’

Am I coping, though? I think about Lukas. He’s at a wedding today, and last night I gave him my number, after we’d talked, after I’d told him about the man I thought I’d seen outside my window, after he’d given me his.

Now I wish I hadn’t. I feel bad enough about leading him on.

I turn to look at Hugh. Lukas had said he wished he could protect me, that he’d never let anyone hurt me. I’d felt safe. But my husband? He’s sitting forward, his eyes fixed on the road. It’s how I imagine he looks in theatre. Scalpel in hand, crouching over a body that’s been split like a gutted fish. Would he protect me? Of course not. He thinks I’m making it up.

Carla greets us with a flurry of smiles and kisses then takes us through the house to the patio. Hugh goes over to Carla’s husband, Connor towards a picnic blanket where the other kids are clustered. I spot Maria and Paddy standing with a few others and join them.

Maria embraces me, then her husband does. They’re talking about work; Maria mentions the conference in Geneva. She begins to describe the work she presented – she mentions anterior descending arteries, calcification, ischaemia – and the others either nod or look confused. There’s an older man standing next to Paddy and I remember him from last year, a barrister, from Dunfermline, and when Maria finishes he says, ‘Sounds utterly impenetrable!’ and everyone laughs. A moment later he turns to me.

‘And how do you fit in? Do you butcher people for a living, too?’

There’s a moment of silence. Kate hadn’t been butchered, but still the word stings. An image of my sister comes and I can’t shake it away. I open my mouth to answer but no words come.

Paddy tries to rescue me.

‘Julia’s a photographer.’ He smiles and turns to me. ‘Very talented.’

I try to smile, but I can’t. I’m still looking at Kate, her flesh torn, exposed, dying. The man I’m being introduced to has his hand out, he’s smiling.

‘Will you excuse me?’ I say. ‘I’m just going to the bathroom.’

I lock the door behind me and lean against it. I inhale deeply then step forward. The window is open; laughter drifts up from the patio below.

I shouldn’t have come here, I should’ve made an excuse. I’m sick of pretending everything’s normal, when it isn’t. I take out my phone. It’s automatic, instinctive, I’m not sure why I do it, but I’m glad. I’ve had a message from Lukas.

‘The wedding’s fun. I’m drunk already. Thinking of you.’

Despite the blackness I’m feeling, joy rushes in, as if to disinfect a wound. It’s not because the message is from him, I tell myself. It’s the simple thrill of being wanted.

By now I know how Kate would’ve replied. ‘I’m at a dreadful party,’ I type. ‘Wish you were here …’

I press send. I rinse my hands in cold water then splash some on my face and my neck. It trickles down, under my dress to the small of my back, lighting up my skin. I look out of the window.

Connor is outside. He’s sitting on the grass with another boy and a girl. They’re laughing at something; he seems particularly close to the girl. I realize it won’t be long until he’s dating, then having sex, and then part of him will be lost to me for ever. It’s necessary, but it fills me with sadness.

He lifts his hand to wave at his father. It strikes me how much he looks like Kate, when she was his age. They have the same slight roundness to their face, the same half-grin that can disappear and reappear in an instant.

He looks like his mother. It shouldn’t be a surprise. Yet it is, and it hurts.

I rejoin the group, but I can’t tune into the conversation. Why had I been so excited to get Lukas’s message? Why had I replied to him? The questions circle and after a minute or two I excuse myself and go to say hello to Connor. He’s with his friends, I’m interrupting him, and I feel bad. I move on, to the summer house tucked away at the side of the garden, between the house and the gate that leads to where the cars are parked. It’s octagonal and painted mint green, filled with cushions. When I get there I see that the doors are open, and that it’s empty.

I sit down and lean back against the wood. The babble of conversation continues. I close my eyes. The smell is of recently varnished wood; it reminds me of the only childhood holiday I can remember from when my mother was alive, a chalet we rented in the Forest of Dean. I can picture her, standing at the stove, boiling water for my father’s coffee while I fed Kate. She’s singing along to a radio, humming to herself, and Kate is giggling at something. We were all alive, then, and mostly happy. But that was before the slow process of dislocation that ended only when my sister’s death left me totally alone.

I want a drink. Right now. I want a drink and, worse, more dangerous, I think I deserve one.