‘Yes,’ she says at last. ‘Yes it’s true. It’s all true.’

‘What?’ Thea explodes. She stands up, knocking over her glass so that it smashes on the floor, red wine seeping across the boards. ‘What? You’re going to sit there and tell us that you dragged us into covering up a murder? I don’t believe you!’

‘What don’t you believe?’ Kate says. She looks up at Thea, her blue eyes very steady.

‘I don’t believe any of it! You were fucking Luc? Ambrose was sending you away? And you killed him for it?’

‘It’s true,’ Kate says. She looks away, out of the window, and I see the muscles in her throat move as she swallows convulsively. ‘Luc and I … I know Dad thought of us as brother and sister, but I barely remembered him. When he came back from France, it was like … it was like falling in love. And it seemed so right, that’s what Dad couldn’t get. He loved me, he needed me. And Dad –’ She swallows again, and shuts her eyes. ‘You would have thought we really were brother and sister from the way he acted. The way he looked at me when he told me …’ She is looking across the Reach, towards the headland, beyond which lies a tent surrounded by police tape. ‘I’ve never felt dirty before. And I felt it then.’

‘What did you do, Kate?’ Fatima’s voice is low and shaking, as if she can’t believe what she’s hearing. ‘I want to hear it from you, step by step.’

Kate looks up at that. Her chin goes up, and she speaks almost defiantly, as if she’s made up her mind, at last, to face the inevitable.

‘I bunked off school that Friday, and I went home. Dad was out, and Luc was at school, and I poured the whole of his stash into that red wine he kept beneath the sink. There was only one glass left in the bottle, and I knew Luc wouldn’t drink it – he was out that night, in Hampton’s Lee. And it was always the first thing Dad did on a Friday night – come home, pour himself a glass of wine, throw it back – do you remember?’ She gives a shaking laugh. ‘And then I went back to school, and I waited.’

‘You dragged us into this.’ Thea’s voice is hoarse. ‘You got us to cover up a murder, and you’re not even going to say sorry?’

‘Of course I’m sorry!’ Kate cries, and for the first time her weird calm cracks, and I get a glimpse of the girl I recognise beneath, as anguished as the rest of us. ‘You think I’m not sorry? You think I haven’t spent seventeen years in agony over what I made you do?’

‘How could you do it, Kate?’ I say. My throat is raw with pain, and I think I may sob at any moment. ‘How could you? Not us – him. Ambrose. How could you? Not because he was sending you away, surely? I can’t believe it!’

‘Then don’t believe it,’ Kate says. Her voice is shaking.

‘We deserve to know,’ Fatima snarls. ‘We deserve to know the truth, Kate!’

‘There’s nothing else I can tell you,’ Kate says, but there’s an edge of desperation in her voice now. Her chest is rising and falling and Shadow patters over, not understanding her distress, and butts his head against her. ‘I can’t –’ she says, and then seems to choke. ‘I – I can’t –’

And then she jumps up and walks to the window overlooking the Reach. She steps out with Shadow at her heels, and slams it behind her.

Thea makes as if to go after her, but Fatima catches at her arm.

‘Leave her,’ she says. ‘She’s at breaking point. If you go after her now, she’s liable to do something stupid.’

‘What?’ Thea spits. ‘Like throw me in the Reach too? Fuck. How could we be so stupid? No wonder Luc hates her – he knew all along. He knew, and he said nothing!’

‘He loved her,’ I say, thinking of his face that night when we saw Kate standing at the corner of the stairs – the mix of triumph and agony in his eyes. They both turn to me, as if they’d forgotten I was there, huddled in the corner of the sofa. ‘I think he still does, in spite of everything. But living with that – with that knowledge all these years –’

I stop. I put my hands to my face.

‘She killed him,’ I say, trying to make myself believe it, understand it. ‘She killed her own father. She didn’t even try to deny it.’

We are still sitting there much later, when there is a noise from the window, and Kate comes back inside. Her feet are wet. The tide has risen, covering the jetty, and the wind has picked up, and I see that her hair is speckled with rain. A storm is coming.

Her face, though, is back to that unsettling calm as she clicks the window shut behind her, and puts a sandbag against the frame.

‘You’d better stay,’ she says, as if nothing has happened. ‘The walkway has been cut off, and there’s a storm coming.’

‘I’m pretty sure I can wade through two feet of water,’ Thea snaps, but Fatima puts a warning hand on her arm.

‘We’ll stay,’ she says. ‘But, Kate, we have to –’

I don’t know what she was about to say. We have to discuss this? Talk to each other? Whatever it was, Kate interrupts.

‘Don’t worry.’ Her voice is weary. ‘I’ve made up my mind. I’ll call Mark Wren in the morning. I’ll tell him everything.’

‘Everything?’ I manage. Kate’s mouth twists in a wry, tired smile.

‘Not everything. I’m going to tell him I acted alone. I won’t bring you into it.’

‘He’ll never believe you,’ Fatima says falteringly. ‘How could you have dragged Ambrose all that way?’

‘I’ll make him believe,’ Kate says flatly, and I think of the drawings, the way Kate made the school believe what she wanted them to, in the face of all the evidence. ‘It’s not that far. I think with a tarp someone could – could drag a –’ But here she chokes. She cannot say the words. A body.

I feel a sob rise in my throat.

‘Kate, you don’t have to do this!’

‘Yes,’ she says, ‘I do.’ And she comes across the room, and puts her hand on my cheek, looking into my eyes. And her mouth flickers in a little sad smile, just for a moment. ‘I want you to know this, I love you all. I love you so much, all of you. And I am so, so sorry, more than I can express, that I dragged you all into this. But it’s time I ended it, for all our sakes. It’s time I made it right.’

‘Kate –’

Thea looks shaken, her face is white. Fatima is standing, and she rubs her hand over her face as if she cannot believe it has come to this, that our friendship – the four of us – is going to end this way.

‘Is this it?’ she asks uncertainly. And Kate nods.

‘Yes. This is it. This is the end. You don’t need to be afraid any more. I’m sorry,’ she says again, and she looks from Fatima, to me, and last of all to Thea. ‘I want you to know that. I’m so, so sorry.’

I think of the lines from Ambrose’s letter. I am so sorry, I’m so very, very sorry to be leaving you like this …

And as Kate picks up the lamp and walks up the stairs, into the darkness, with Shadow a glimmer of white at her heels, I feel the tears begin, falling down my face like the rain that is spattering the windows, for I know she is right. This is it. This is the end. And I can’t bear for it to be so.

WHEN I EVENTUALLY make my way up the stairs to Luc’s room, I’m not expecting to sleep. I’m expecting another night of lying there, questions churning in my head as Freya slumbers beside me. But I’m tired – more than tired, exhausted. I climb into bed fully clothed and as soon as my head touches the pillow, I fall into uneasy dreams.

It’s some time later – I’m not sure how late – that I am jerked awake by the sound of voices in the room above. They are arguing, and there is something about the voices that prickles at the back of my neck.

I lie for a moment, dragging myself out of disturbing dreams of Kate and Ambrose and Luc, trying to orientate myself, and then my eyes adjust. Light is filtering through the gaps in the floorboards of the room above, flickering as someone prowls back and forth, voices rising and falling, and a thud that makes the water in my glass ripple, as of someone hitting a wall in barely contained frustration.