‘Or what?’ he says sarcastically. ‘You’ll call the police? I don’t think so.’

‘Luc …’ Kate’s voice is wary.

‘God,’ he spits. ‘I came to apologise. I was trying to help. Just once – just once – you’d think I’d learn from my mistakes. But no – you haven’t changed, none of you. She whistles, and you come running, all of you, like dogs.’

‘What’s going on?’ It’s Fatima from behind us, with a staggering Thea on her shoulder. ‘Is that … Luc?’

‘Yes, it’s me,’ Luc says. He tries for a smile, but his mouth twists, and it comes out halfway between a sneer and the expression someone makes when they’re trying not to cry. ‘Remember me, Fatima?’

‘Of course I do,’ Fatima says in a low voice.

‘Thea?’

‘Luc, you’re drunk,’ Thea says bluntly. She steadies herself on the stile.

‘Takes one to know one,’ Luc says, taking in her muddied dress and smeared make-up.

But Thea simply nods, without rancour.

‘Yes. Maybe it does. I’ve been on the edge enough times to know you’re pretty fucking close right now.’

‘Go home, Luc,’ Kate says, ‘sober up, and if you’ve got something to say, say it in the morning.’

‘If I’ve got something to say?’ Luc gives a short hysterical laugh. His hands, as he runs them through his tangled dark hair, are shaking. ‘If? What a fucking joke! What would you like to talk about, Kate – maybe we could have a nice chat about Dad?’

‘Luc, shut up,’ Kate says urgently. She looks over her shoulder, and I realise, unsettlingly, that it’s not impossible that anyone will be out at this time of night. Dog walkers, people from the dinner, night fishermen … ‘Will you please be quiet? Look – come back to the Mill, we can talk about this properly.’

‘What, don’t you want the world to know?’ Luc says mockingly. He puts his hands to his mouth, making a trumpet, and shouts the words out to the night. ‘You want to know who’s responsible for the body in the Reach? Try right here!’

‘He knows?’ Fatima gasps. Her face has gone pale as clay. I feel my stomach dropping, and suddenly I feel as sick as Thea looks. Luc knows. He has always known. Now suddenly all his anger makes sense.

‘Luc!’ Kate’s voice is a sort of screaming whisper. She looks beside herself. ‘Will you please shut up for God’s sake? Think about what you’re doing! What if someone hears?’

‘I don’t give a fuck who hears,’ Luc snarls back.

Kate’s fists are clenched, and for a minute I think that she is going to hit him. Then she spits out the words as though they are poison.

‘I’ve had it with your threats. Get away from me and my friends, and don’t you dare come back. I never want to see you here again.’

I can’t see Luc’s face in the darkness, only Kate’s, hard as stone and full of fear and anger.

He doesn’t say anything. For a long time he only stands, facing Kate, and I feel the wordless tension between them – strong as blood, but now turned to hate.

At last though, Luc turns, and begins to walk away into the darkness of the marsh, a tall black figure melting into the night.

‘You’re welcome, Isa,’ he calls back over his shoulder as he disappears. ‘In case I didn’t say. Looking after your baby – it was nothing. I’d be happy to take her again.’

And then the sound of his footsteps fades away into the night. And we are alone.

AS WE WALK the last short stretch back to the Mill, I try not to let Luc’s words get inside my head, but I can’t help it. Every step is like an echo of that night, seventeen years ago. Sometimes what happened then seems like something done in another place, another time, which has nothing to do with me. But now, stumbling across the marsh, I know that is not true. My feet remember that night, even if I have tried to forget, and my skin crawls with the memory of the hot summer stickiness.

The weather was just the same, the insects still buzzing in the peat, the warm air a strange contrast to the chilly moonlight as we stumbled over stiles and ditches, our phones casting a ghostly glow over our faces as we checked and checked again for another message from Kate, one that would tell us what was going on. But there was nothing – just that first, anguished text: I need you.

I had been ready for bed when it came through, brushing my hair in the light of Fatima’s reading lamp as she ploughed through her trigonometry homework.

The beep beep! shattered the quiet of the our little room, and Fatima’s head came up.

‘Was that yours or mine?’

‘I’m not sure,’ I said. I picked up my phone. ‘Mine, it’s from Kate.’

‘She’s texted me too,’ Fatima said, perplexed, and then, as she opened the text, I heard her indrawn breath at the same time as mine.

‘What does it mean?’ I asked. But we both knew. They were the same words I had texted the day my father phoned and told me that my mother’s cancer had metastasised, and that it was now a matter of when, not if.

The same words Thea had texted when she had cut herself too deeply by accident, and the blood wouldn’t stop flowing.

When Fatima’s mother’s jeep crashed on a remote country road in a dangerous rural area, when Kate had trodden on a rusty nail, coming back one night from breaking out of bounds … each time those three little words, and the others had come, to comfort, to help, to pick up the pieces as best we could. And each time it had been OK, or as OK as it could be – Fatima’s mother had turned up safe and well the next day. Thea had gone to A&E, armed with some story or other to cover up what she had done. Kate had limped back, held up between us, and we had bathed the scratch with TCP and hoped for the best.

We could solve anything, between us. We felt invincible. Only my mother, dying by slow degrees in a London hospital, remained like a distant reminder that sometimes not everything would be OK.

Where are you? I texted back, and as I was waiting for an answer, we both heard the sound of running footsteps on the spiral stairs above, and Thea burst into the room.

‘Did you get it?’ she panted. I nodded.

‘Where is she?’ Fatima asked.

‘She’s at the Mill. Something’s happened – I asked what, but she hasn’t replied.’

I hurried back into my clothes and we climbed out of the window and set out across the marsh.

Kate was waiting for us when we arrived at the Mill, standing on the little gangway that led across the water, her arms wrapped around herself, and I knew from her face, before she even spoke, that there was something very, very wrong.

She was bone white, her eyes red with crying, and her face was streaked with the drying salt of tears.

Thea began to run as we caught sight of her, Fatima and I jogging after her, and Kate stumbled across the narrow gap of water, her breath hitching in her throat as she tried to say, ‘It – it – it’s Dad.’

Kate was alone when she found him. She hadn’t invited the rest of us that weekend, making an excuse when Thea suggested coming over, and Luc was out with his friends from Hampton’s Lee. When Kate arrived at the Mill, bag in hand, she thought at first Ambrose was out too, but he was not. He was sitting on the jetty, slumped in his chair, a wine bottle on his lap, and a note in his hand, and at first she couldn’t believe that he was really gone. She dragged him back into the Mill, tried mouth-to-mouth, and only after God knows how long begging and pleading, and trying to get his heart to start again did she break down, and begin to realise the hugeness of what had just happened.

‘I’m at peace with my decision,’ the note read, and he did look at peace – his expression tranquil, his head flung back for all the world like a man taking an afternoon nap. ‘I love you …’

The letters trailed almost into incoherence at the end.

‘But – but, why, and how?’ Fatima kept asking. Kate didn’t answer. She was crouched on the floor, staring at her father’s body as though, if she looked at it for long enough, she would begin to understand what had happened, while Fatima paced the room behind her, and I sat on the sofa, my hand on Kate’s back, trying without words to convey everything that I didn’t know how to express.