Clouds of midges hover over the sun-speckled water of the canal. Nathan’s not here yet, and while I wait I sit on a slatted bench, stifling yawn after yawn. A narrow boat with orange flowers painted on the side drifts lazily past, the smell of bacon wafting across the water. I watch as it stops at a lock. A grey-haired woman and a yapping Yorkshire terrier alight the boat while a man in a flat cap stays on board. A movement on the bridge catches my eye. A shadowy figure. I can’t make them out in the brightness of the sun, but it seems they are looking straight at me. Despite Vanessa’s reassurances I am edgy as I stare back at them but when they raise their arm and wave and step forward I see it’s only Nathan, and I slowly exhale in relief.

‘Nice to see you again,’ Nathan says as he joins me, kissing me on the cheek as I stand. ‘I have something for you.’ He swings the rucksack from his shoulder and pulls out a bottle of water. ‘So you don’t overheat again,’ he says and I laugh, instantly at ease.

Making small talk, we walk. The sunshine has brought out families and the towpath is teeming with toddlers on scooters, children on bikes. Dogs strain against leads, desperate to jump into the water.

‘Look!’ Nathan stops. A brood of ducklings bob up and down struggling to keep up with their mother as she paddles through the water at an alarming rate.

‘Oh, that little one’s getting left behind.’ I point.

‘Let’s slow her down.’ Nathan reaches into his rucksack again and produces a bag of bread.

‘Here.’ He hands me a crust, and I break it into small pieces before tossing them into the canal where they float on the top of the murky water. The duck weaves towards them, her babies close behind as we watch the bread being gobbled up before the family swim away, disappearing behind reeds.

Nathan stuffs the empty bag into his rucksack. ‘Ice cream?’

‘I’d love one.’ I sit on a bench as Nathan queues at the kiosk; thanking him as he returns with a cone, ice cream swirled into a point, chocolate flake sticking out like a flag.

I swirl my tongue along the edge of the cornet as Nathan bites into his ice cream. He winces.

‘Brain freeze?’

He nods, curling his lips over his teeth.

‘Press your tongue against the roof of your mouth,’ I say. ‘Harry’s always rushing his cornets. It helps generate heat. It really works.’

A few moments later he’s ready to talk. ‘That did help. It’s a sign of getting older, isn’t it? Not being able to bite into anything too cold. When I was his age,’ He nods towards a young boy chomping away on a Fab lolly, hundreds and thousands scattering over the grass. ‘I used to bite on lollies just like that. Who’s Harry?’

‘So you’re still in touch with Sam’s family?’ He frowns after I’ve explained.

‘Yes. I didn’t see them for ages after… after me and Sam broke up but I can’t imagine not having Harry in my life. Do you still see Callie’s family?’

‘No.’ His reply is curt but I push him to elaborate.

‘Why not?’

‘They didn’t want to see me after the accident. Too painful, I suppose.’

‘Did she have any brothers? Sisters?’ I watch a brilliant blue dragonfly dip towards the water as I ask, not quite able to look him in the eye. The deceit doesn’t sit well with me.

‘She had a sister, Sophie, but I haven’t seen her since before the accident. She couldn’t handle it. Didn’t even come to Callie’s funeral to pay her last respects. Sent a wreath as though that made up for it.’

‘Does she live close by, Sophie?’

‘I’ve no idea where she is.’

I take a deep breath. ‘And Callie’s accident. What happened?’

Nathan breaks the remainder of his ice-cream cone into pieces and tosses them into the water.

‘She was driving and ran into a tree. It was a terrible night. The roads were treacherous.’

‘That’s awful. Where was she going?’

‘Does it matter?’ His tone is terse. I feel I am interrogating him but it has to be done, for Tom and Amanda’s sake. I try again.

‘I just wondered if she’d been on her way to meet you?’

‘No.’ His voice breaks and he leans forward and drops his head into his hands, and I feel guilty for pressing him

‘You must miss her very much.’ I reach out and squeeze his arm. ‘You were together a long time, weren’t you?’

He straightens his spine and huffs out air. ‘Five years. Not that it counted for much in the end. I didn’t get a say.’

‘In what?’

‘In anything. Where she was buried. She’d have hated the church service. She wanted to be cremated and her ashes scattered near the ocean. We talked about it once after watching a film where someone died young. Her parents even allowed her to be cut up. Imagine that. Slicing out parts of her and handing them out as though they’re bits of meat from the butcher’s counter.’

‘You don’t agree with organ donation?’ My voice is sharp.

‘It’s not natural, is it? Doctors playing God.’ He thrusts his hands deep in his pocket and leans back on the hard wooden support. ‘She was, well, she was just so perfect, beautiful, you know? And to think of her not being whole. It’s not right.’

‘I can’t imagine how hard it must be for you. But she must have saved lives.’

‘I know. She’d have liked that. I just can’t bear the thought of her not being Callie any more. And I should have had a say. We were going to get married. Tom and Amanda were handed the pen and the consent forms, and I didn’t even get asked my opinion. I remember when it was all over and the nurses handed Tom Callie’s belongings; he passed them to me as if all I was good for was holding her things. I crushed them so tightly to my chest I thought my ribs might snap. I was so bloody angry.’

We sit in silence. I don’t know what to do. I don’t know what to say, and I wonder whether I should just go home. Tom and Amanda will come to terms with everything eventually, and Nathan’s still grieving. My detective work doesn’t seem to be getting me anywhere.

I clear my throat, and Nathan twists to look at me.

‘Sorry. This wasn’t how I planned the day. Talking about my ex, but I feel comfortable with you, Jenna, in a way I don’t usually feel with people,’ he says and I wonder if he feels it too; this invisible thread that binds us together.

‘It’s OK. Really.’

‘No it isn’t. Hungry? I can make it up to you with food.’ He stands and reaches out both hands and pulls me to my feet. ‘There’s a great pub and it’s not too far.’

* * *

Conversation flows easily over dinner. I feel I’ve known Nathan for ever and I suppose, in a way, I have. Each time I mention Callie or Sophie, Nathan changes the subject, and after a while it’s a relief to talk about the mundane: TV, music. I’m surprised to find I’m enjoying myself, and I wonder if he is too.

There’s a change in the atmosphere as our plates are cleared, and as we both reach for the bill our hands brush and there’s a spark. Nathan asks if I’d like to go back to his for coffee. I feel a pang of longing and I tell myself it’s only because I am feeling Callie’s feelings. I try to think of Sam, but as we leave the pub I can’t feel anything except the heat of Nathan’s hand through my jacket as it rests on the small of my back. I can’t help wishing he were touching my skin.

* * *

At Nathan’s I sit on the end of the sofa with my feet tucked under me, feeling completely at home.

‘Wine?’

‘Not for me thanks.’ The warm flush of alcohol would settle my nerves but it’s strictly off limits after my transplant. ‘It gives me migraines,’ I lie. Telling people I never drink always causes them to eye me suspiciously, and leads to a multitude of questions.

‘That must be rough. A girl at my office gets migraines. I’ve never had one, thankfully. I’ll make some tea.’

Alone, I try to recall why Tom said Nathan had left the wedding. Wasn’t that a migraine? Or did he feel sick. I scrunch up my eyes but the memory dances just beyond my fingertips and I can’t quite reach it.

When Nathan sits back down he’s so close our thighs press together, and I’m hot and cold and excited and terrified and everything but thirsty, but that’s OK, my hand’s shaking too much to pick up my drink anyway.

‘Can I ask you something personal, Jenna?’

My hand instinctively flutters to my chest, making sure my scar is covered. ‘Yes.’

‘Are you still in love with Sam?’

The question hits me like a punch in the gut and I open my mouth to say no, but the word sticks to my tongue like peanut butter and I can’t spit it out. Instead I shake my head but I don’t know if I’ve convinced Nathan any more than I’ve convinced myself.

Nathan crosses the room, bends and fiddles with the silver iPod that rests on a Sonos Dock. Laid-back folk music fills the air, and my feet begin to tap a rhythm as though they’ve heard the song before.

‘Do you get lonely?’ Nathan asks, picking up the conversation where he’d left it.

I think of the times I’ve lain on the bathroom floor feeling as though I might die. The nights I’ve woken up, pressing my hands against my chest, checking my heart’s still beating, terrified it will stop. The dark and chilly evenings curled on the sofa alone.

‘I’m OK on my own,’ I say but my eyes fill with tears and my voice breaks, and I hate myself for feeling so vulnerable.

Nathan stretches his arm around me and strokes the back of my neck until my skin feels so hot I think it must surely be burning his fingers. I’m stiff at first. Awkward. But I allow myself to lean into him. He’s not Sam but there’s a familiarity about him that makes my body ache. It’s been so long since I have been touched. We sit still at first. Silent.

‘Jenna,’ he whispers, and I twist my head to look at him.

I’m scared and excited, and as he leans in to kiss me I pull back not sure this is what I want. I touch his face. He leans in again; his lips brush mine, and I am lost. He pushes me back until I’m lying on the sofa; my hands twist in his hair, and his tongue thrusts into my mouth. His hands are everywhere and my body is screaming out for this but as he tugs at the button of my jeans my ecstasy plunges into terror. Is my heart strong enough? Will I die? I bat his hand away and try to sit up but he kisses me again and begins to unbutton my blouse. I can’t let him see my scar, and I slap my own hand over my buttons to block him but I can’t stop kissing him. Can’t seem to tell him it’s too much. Too soon. I’m not ready. I was never meant to like him but I want this so badly my hips rock up. I tug his shirt from his jeans, feel the warmth of his skin. I count the beats of my heart as Nathan rolls my nipples between his thumb and forefinger; I stop counting as he trails kisses down my neck and by the time his hand snakes his way inside my jeans my initial whimpers of fear morph into cries of passion, and I no longer care that my heart is galloping. I gasp and part my legs and feel myself falling, falling, falling over a cliff.

* * *

It is late as I sit at my kitchen table, moonlight flooding through the window, a half-empty mug of chamomile tea in front of me. I close my eyes and run two fingers over my chest trying to feel what Nathan felt. Did he notice my scar? The skin feels thinner to me. Puckered. But I know it’s there. My thoughts are so chaotic. I can’t imagine how I’ll sleep tonight.

‘Stay,’ Nathan had begged.

‘I can’t.’ I had wriggled out of his grasp and called a taxi. Nathan had offered to drive but I insisted on a cab. I didn’t want the awkwardness of feeling obliged to invite him in.

‘It’s not like you’ve got anyone to rush home to, is it?’ He had frowned.

‘No.’ I had nipped the soft flesh of my bottom lip between my teeth. I hadn’t known what to say. I hadn’t wanted the awkwardness of getting undressed. Questions about my scar, and besides it’s Callie’s birthday tomorrow and I need to leave my flat early to get to Tom and Amanda’s.

‘I’ve got a day off on Monday?’ I said. ‘Are you owed any more hours?’

‘Yes, Monday’s good but what about this weekend too?’

‘I’ve got plans. Sorry,’ I added as his face fell.

The taxi honked its arrival and Nathan had walked me to the car, and kissed me long and hard.

‘Any chance of you getting in today, luv?’ The driver had called and I climbed into the back of the car.

Now, as I rinse my cup at the sink I glance out of the window. Across the road, out of the blackness, a shadow moves. A figure. I stand motionless. My light is off so they shouldn’t be able to see in but the hairs on the back of my neck prick up. They lean against the wall, staring up at my window. I can’t properly see them in the darkness, and it’s difficult to tell whether it’s a man or a woman. My chest feels tight. Who is it? Can they see me? I force myself to look away. But my eyes are drawn back to the window. They’re still there. I tell myself they’ve probably stepped out for a cigarette but I can’t see a tell-tale red glow. My body is rigid. Muscles ache. But I remain standing, watching them, watching me until I blink and they’re gone and I wonder if they were ever there at all. Vanessa said there is nothing to be scared of, but my heart races all the same.